Welcome to my autumn weather forecast for 2023.

First thing to note, as always, is that seasonal forecasting remains experimental. Whilst my forecast for June was good, and for August was respectable – for July I predicted a hot month. Aha. Though at least I thought there would be some rain, albeit of a thundery variety rather than Atlantic systems.

So, some of this forecast will be wrong – due to events, it is impossible to give accurate long-range forecasts, but you can give a general guide based on current weather patterns, background signals, etc.

I’m not sure what went wrong in July – did I misread the models? Perhaps but so did every other forecaster who I take notice of, in that case. I know there were unusual plunges of cold air into North America late June, which fired up the jetstream – and then there was some really anomalously warm waters off the coast of North America, which likely gave low pressure systems their oomph this summer.

That’s my working theory on what went wrong anyway.

So whatever I say here, take with a huge pinch of salt.

Thanks to Sarah for the superb photograph, and to all those that sent in – there were a few particularly excellent ones to choose from.

Background Signals

El Niño is still developing and is probably going to be a strong event. I’m not sure that it has too much effect on the UK weather patterns in autumn, perhaps a slightly increased chance of westerly flows later on.

Sea surface temperatures are still warmer than normal around the UK, which increase the chance of warmer than normal temperatures over the UK.

The Quasi-Biennial Oscillation is now in easterly mode – I’ve seen some people on weather forums blame that for our summer weather, but I’m not buying it. Though perhaps it can increase the chance of blocking highs or easterly flows during autumn.

As always, hurricanes/tropical storms and their remnants can affect our weather and add extra uncertainty, especially in September.

September

Speaking of hurricanes, Franklin is the major cause of our hot start to September, pushing high pressure east and allowing us to tap into continental warmth/heat.

So an increasingly hot and sunny start to September, very possible that the highest temperature of the year is recording during September, though I think we’ll stay short of the UK all-time September maximum – which is 35.6’C. Some warm nights too, though some early morning mist/fog/low cloud in places.

Towards the middle third, there will be (small) chances of thundery showers before the heat gradually faces, and by around mid-month or just after, we should be in something more changeable – perhaps briefly unsettled.

In the latter part of the month, probably some variation with some showers, but a return to warm and dry looks more likely overall. Bear in mind that hurricanes/tropical storms far to our west add uncertainty to this.

Overall I expect well above-average temperatures, above-average sunshine, and below-average rainfall – unless you catch a particularly heavy downpour during mid-month.

Confidence level of 85%.

October

Signals are weaker for October though there is a fairly notable signal for high pressure close to the east of the UK.

A dry start may give way to a spell of more unsettled weather into the first half of October, perhaps some very heavy, showery rain at times, and quite windy. Likely mild and occasionally warm.

In the latter half of October, it seems more likely that the high to our east will push west somewhat, meaning rain stays to our west most of the time, and it should generally be dry, mild with some overnight mist/fog.

Overall I expect above-average temperatures, around average sunshine and around or slightly below-average rainfall.

Confidence level of 60%. The main risk is that the high pressure block is further east and low pressure systems get stuck over the UK – bringing a wetter month than I expect.

November

November I think will more likely start dry with high pressure close by. Overnight frosts with some morning mist/fog patches possible. Some sunny days, some cloudy days, temperatures around normal for the time of year.

During the latter part of November, the jetstream should pick up and we’ll have a more westerly flow – some rain at times from weather fronts though I suspect the bulk of the heavy rain and strong winds will be towards Scotland. Generally mild/very mild under such a set-up. Uncertain on cloud/sunshine amounts.

Overall I expect slightly above-average temperatures, around average sunshine, below-average rainfall.

Confidence level of 50%.

Overall and Early Winter Thoughts:

So drier and warmer than normal for autumn, is what I expect. We shall see!

Early thoughts for winter are mostly for a mild and dry winter with a strong signal for higher than normal pressure over Europe.

I wouldn’t preclude a cold spell, and there will be some rain at some point, but overall drier and milder than normal seems the most likely outcome – albeit it’s 3 months away!…

Welcome to my Summer Weather Forecast 2023. I think you’ll like it.

Some of this forecast will be wrong. That is the case for all seasonal forecasts (unless a forecaster gets lucky). We can have some confidence on general trends, but picking out short-term features or getting the timing right of changes, becomes impossible after a couple of weeks. And then the general trends can change – what you think was likely, then gets disturbed by a major event somewhere in the world, which then adjusts the jetstream, etc, etc.

But hopefully I can give a reasonable guide.

I’m fairly happy with my spring forecast. It was cold to start March, and wet to end as I thought – though wetter than I expected. April I predicted average temperatures, slightly above average rainfall and slightly below average sunshine – which was broadly the case. May I thought we’d be in an easterly flow, which did dominate and still does into June, but low pressure was further south than I expected – I had expected it to be a bit closer and hence warmer with showers for the latter half.

Thanks to everyone that sent a photograph in – my choice is Dave’s with a gloriously sunny sky, though with hints of showers to come.

Background Signals

There isn’t really a lot to talk about, though the key factor is extreme temperatures don’t have the same base as they did last year, as the soil moisture profile is higher over Europe, which should just temper the possibility of extreme temperatures.

However, on the flip side, sea surface temperatures are higher, if not much higher, across much of the eastern Atlantic, from Spain/Portugal, all the way through to Ireland, which I’d suggest makes hot weather a little more likely.

It is contested, but personally I believe that winter sudden stratospheric warming events have an imprint into summer months, especially late season SSWs, like we had, and increase the propensity of blocking highs to our north (exactly as has happened in recent weeks). This doesn’t always lead to glorious summer weather for us (2021 for example) but can lead to drier, summer and warmer/hotter weather, depending on exactly where high pressure situates.

I struggle a bit to understand the atmospheric angular momentum theory, but if I understand correctly, the current positive and predicted strongly positive phase, should lead to high pressure to our east, low to our west – a hot but sometimes thundery set-up, down the line in future weeks. I stress that I don’t really understand this that well though.

The other factor is the developing El Niño, which hasn’t occurred yet, but is likely to be confirmed during the summer. It doesn’t have as much impact here as elsewhere in the world (at least as far as we know), but maybe we can infer a slightly greater chance of showers later in the season, at a push. But even that, depends on how strong El Niño becomes, and we don’t know.

All in all, background signals seem to point more to a hotter summer than normal. Though I think long-term models and predicted pressure patterns are more important for this season…and they also point to hotter than normal weather.

An attempt at some details:

June

High pressure dominates the start of June, some cooler and cloudy mornings, but generally sunny and warm afternoons. This changes around 10th June to a more south-easterly flow, with temperatures on the up, very warm or quite hot, but also some thundery downpours in the mix – potentially quite severe in places, but also the potential to miss everything and just enjoy varying amounts of quite hot sunshine.

After mid-month, temperatures generally staying very warm – a few less warm days possible, some quite days also possible, but broadly very warm, sunny spells – a few days likely featuring some heavy, thundery showers, perhaps even a day or two of heavy, thundery rain spreading up from the south, but overall plenty of very pleasant weather is the more likely general outcome.

Overall I expect a warmer than average month and sunnier than normal average. Low confidence on rainfall totals, as it will depend on if you catch any particularly torrential downpours, so perhaps best to suggest more dry days than average.

Confidence levels around 80% – main uncertainty is over whether the mid-month thundery showers turn into a more widespread low pressure system.

July

July looks to see high pressure close to our east or north as the dominant pressure pattern, which means plenty of hot, sunny weather is likely.

Perhaps during the first part of the month, we see high pressure more centred to the north/north-east, which will lead to it generally being very warm/quite hot, though with occasional thundery downpours for us in the south – there is a signal for a wetter than normal summer over Spain/France, so I’d expect we’ll import thunderstorms or at least some instability on occasion from continent.

During the middle and second half of the month is when the hottest part of the summer is more likely, with high pressure more likely to be to our east – low to our west, and depending on where the low is, those Iberian heat-pump scenarios similar to last year (and most summers but last year was notably so) will be more likely – so short very hot spells followed by short unsettled, possibly thundery spells, followed by fine weather – is the more likely general pattern.

Generally the signal for rainfall is higher in the south of the UK than the north, so those who like their holidays in Scotland may approve this year.

Overall for July, I expect above-average temperatures, slightly above-average sunshine and around the average amount of days with rain falling – with rainfall totals dependent on how intense any downpours in your local area are.

Confidence level 75%. I wouldn’t rule out it being the hottest July ever overall – but without the hottest day being recorded. 37’C or so with the “perfect” set-up seems plausible, but 40’C like last year seems too much of a stretch…as it stands.

August

Weaker signals for August, but overall I think the balance for the first half of the month sees more very warm/hot sunny days, though likely some days in the warm with showers kind of theme – the hotter days may also have some thundery downpours too.

Low pressure may be a bit closer to our south-west for the latter month, this bringing more southerly flows – so some hot and humid days, but also some wet days, or at least some thundery downpours. Pretty low confidence though.

Overall for August, I expect above-average temperatures, around average or slightly-below average sunshine, and slightly above-average rainfall.

Confidence level 40%.

Summary And Autumn Thoughts

So, a hot summer but with an increased chance of thunderstorms, I think would be the headline.

Of course, I could be totally wrong. And things change unexpectedly. We shall see.

An early look at autumn currently suggests a warmer but wetter than normal September, and a warmer and drier than normal October/November.

No point in thinking about winter until we know how strong El Niño will be, as that can have an effect on our winter.

Enjoy your summer!…

Welcome to my Spring weather forecast 2023, for Reading and the surrounding areas.

Firstly a reminder that seasonal weather forecasting remains experimental and probably always will be – however there are normally general trends that look more likely on a seasonal basis, especially in the 1-2 month timeframe.

Some of this forecast will be wrong. My winter forecast wasn’t bad – December was pretty accurate, as was the first half of January and latter half of February – though there was a good 3-4 weeks that I expected to be wet, that were actually dry. I don’t think I saw any seasonal forecast suggesting February would be dry – and I think I read that it was the driest for 30 years.

Also thank you to everyone that sent photographs in, even if half of them didn’t have any weather in them! Thanks to Isabel for the photograph – do drop me a message so I know which charity to donate to.

Background Signals

The main background signal is the sudden stratospheric warming event that started in the middle of February, and we have just had another bout of warming up in the stratosphere. This greatly increases the chance of colder flows from northerly and/or easterly directions, and could impact on and off for around 8 weeks.

We still have La Niña, which I think can increase the chance of westerly flows in March – though this goes against the SSW, so, hmmm, not sure on this. There are hints of El Niño developing towards summer, but this shouldn’t impact spring.

The MJO currently is going into phase 7/8 at a high amplitude, which from my understanding increases the chance of colder flows from northerly and/or easterly directions – but maybe the SSW has impacted the MJO anyway?

March

March is very much expected to start on the cold side, snow falling is very possible, overnight frosts likely at times – though sunny spells during the days also, which with the strengthening sunshine at this time of year means any settling snow shouldn’t last too long.

Towards mid-month, milder and wetter weather will try to push up from the south-west, and where this hits the cold air, there could be heavy, disruptive snow – exactly where the battleground will be is uncertain – it is always more likely to be further north than us, but we are certainly in the game. But likewise, maybe low pressure systems don’t quite get this far north, the cold weather stays and the heavy snow ends up in northern France.

If the snowy battleground is much further north, say Scotland (not especially likely), then we may sneak a very mild day or two.

For the latter part of the month, I expect the colder air to move back south at times, perhaps easterly winds setting in – at this point rain will be more likely than sleet/snow, but wintry showers could still be mixed in, overnight frosts still possible. Temperatures sometimes around average, sometimes below average.

Overall I expect below average temperatures, around average rainfall and around average sunshine.

80% confidence.

April

For the first half of April, I still think we’ll be seeing the hangover of the SSW event, with high pressure to our north, and low pressure either to our south or over the south of the UK.

This means generally fairly cool conditions, with rain or showers at times – an outside chance of some wintry showers, and frost still possible on any clear nights.

The second half of the month has much weaker signals, but I’d favour something a bit drier with some warmish sunshine at times, but still some heavy showers on some days.

Overall I expect around average temperatures, slightly above average rainfall and slightly below average sunshine.

70% confidence.

May

May I still think will have high pressure to our north and low pressure to our south – though by this time of year an easterly flow tends to be warm rather than cold, as the continent will be warming up.

So a warmer than normal month overall but also a showery month – low pressure probably close enough at times for spells of general rain, but more likely the month will be predominantly warm/very warm, sunny spells but with heavy/thundery showers quite often.

Overall I expect above average temperatures, above average rainfall (though this assumes some of the showers being very heavy) and around average sunshine.

60% confidence.

Early Signs For Summer

At this stage I’d suggest that a repeat of last year’s 40’C is unlikely, due to there being more rain over Spain this spring, and hence soil and sea surface temperatures probably lower than last year.

However, I still think hot and therefore heatwave conditions more likely than normal, just not quite to that extreme – particularly June and July.

August maybe more showery, especially if El Niño becomes a force.…

Welcome to my Autumn 2022 weather forecast.

Finally it’s time to cool down after a boiling hot summer – I think summer 2022 will go down in history as one of the best ever summers, assuming you count sunshine and heat as “best”.

Regular readers will be aware that seasonal forecasting is fraught with huge amounts of challenges, I hope to get the main themes right, and more details right than wrong – but sometimes I get it completely wrong.

Thankfully my summer 2022 forecast was pretty good – including picking up the heatwave potential for the middle of July and suggesting “some unusually hot weather”. August wasn’t so well-forecasted, but there were very conflicting signals when I wrote the forecast, and I stressed the high levels of uncertainty. Once we got into July, I was pretty confident that August would see more hot and sunny weather.

And that is a difficulty – a certain type of weather might be more probable in 3 month’s time, in my view, but then actual weather events between times change my expectations. So do take this forecast with a good bucket of salt.

Thanks to Isabel for the photograph – a donation of £15.00 has been made to Readifood as a token of my appreciation – and thank you to everyone who sends in photographs. I know I don’t always reply, but I do appreciate them.

Right…action.

Background signals

Firstly, sea surface temperatures are notably higher than usual around the UK, so this increases the chances of warmer than normal weather this autumn.

La Niña continues, and this tends to increase the chances of high pressure close to the west of the UK in late autumn.

The Atlantic hurricane season was expected to be busier than normal, though so far is not, and ex-hurricanes (or tropical storms) can affect previously-expected weather patterns, depending on how they interact with the jetstream. And they increase uncertainty, mostly for September.

September

September starts unsettled, with low pressure close to the west of the UK, bringing warmth, some humidity but also plenty of heavy/very heavy showers, possibly with some thunder. Some warm sunshine/hazy sunshine in between though.

The middle of the month is more uncertain, due to some Atlantic hurricanes/tropical storms far to our west. My current expectation is for a short dry spell, perhaps a little on the cool side, followed by something warmer but wetter once more. A brief hot spell cannot be ruled out during this period.

Towards the end of the month, a reversion back to what we had at the beginning feels more likely, some dry/sunny warm/very warm days mixed in but plenty of showers, and possibly some general rain too. A trend to it being drier towards the very end of the month.

Overall I’m expecting above-average rainfall (the shock!), above-average temperatures and somewhat below-average sunshine.

Confidence level 70% – though lower for mid-month.

October

October looks a much drier month, with the Azores high often building across. It likely becomes cooler, perhaps a bit below-average for a while, with north-westerly or maybe weak northerlies at times. Also quite cloudy, though some sunshine – and some chilly nights. The odd weak weather front but nothing too much expected in the way of rain.

Suggestions that the second half will be warmer than normal, with high pressure stronger over Europe and more of a south-westerly flow – though this likely means at least some rain/showers at times, though I still think drier than normal overall.

Overall for the month, I’m expecting below-average rainfall, slightly above-average temperatures and around average sunshine.

Confidence level around 70% again.

November

For November I’m still expecting high pressure to be dominant close to our south and especially to our west, which means cooler north-westerly/northerly flows more likely than normal – not too dissimilar to the last two Novembers.

So some overnight frosts and chilly but sunny days. But also some areas of rain/showers pushing down at times, from a fairly active jetstream.

Suggestions that the low pressure may set up close to the south-east at times in the latter half of November, a weak suggestion at the moment, but this kind of set-up could bring a wetter than normal end, and colder than normal – perhaps even some wintriness.

Overall I’m expecting slightly above-average rainfall, slightly below-average temperatures and around average sunshine.

Confidence level around 60% – bit of an unusual signal for the end of November so a bit wary there.

Winter Thoughts

Clearly winter is a long way away, though it is looming – perhaps more than most seasons, given the energy bills.

Early suggestions are that December is on the dry side, with a mixture of mild and cold spells.

January and February currently look more likely to be on the wet and mild side.

Well, that’s all. Remember – some of this will be wrong. The perils of long-term weather forecasting. But hopefully more is right than wrong.

If you want a summary – then a warm and wet September, a dry October and a mixed though chilly November.…

Welcome to my weather forecast for Summer 2022.

A week later than I prefer, but well, life got in the way. Better late than never.

Firstly a reminder that not all of this forecast will be correct. Accurate seasonal forecasting is beyond the limits of our abilities, but we can have a good idea of the more likely patterns ahead.

Alas, events occur that can completely break a seasonal forecast – such as sudden stratospheric warming events in winter. Atlantic hurricanes can also change the course of previously expected weather.

So do bear in mind that seasonal forecasting is experimental. Some of this should be good, but some will definitely not be. My aim is to get more right than wrong.

I’m much happier with my spring forecast than I was for my winter forecast. It feels as though I got more right than wrong, including the warm spell at the end of March and the general drier and warmer feel across the season.

Next, thanks to Rose for the glorious photograph. A £15 donation has been made to Sport In Mind as a thank you. And thanks to all those that sent photographs in for the summer forecast, and even more to those who send them in without reward (other than your name in lights!) for the regular forecasts.

Background Signals

There are always less background signals driving our weather at this time of year

La Niña is the main background signal affecting global weather conditions, as it has been for nearly 3 years now. Currently on the weak side, a weak La Niña would suggest high pressure close to the south of the UK during June is somewhat more likely, with low pressure to the north – I think this flips somewhat during July and August, in theory, though I’m not entirely sure I’ve understood that correctly.

Sea surface temperatures around and particularly to the west and north-west of the UK, are much warmer than normal, which suggests a greater chance of high pressure around and to the south of the UK than normal, I believe – and subsequent warmer conditions.

The Madden-Julian Oscillation can help predict the more likely weather outcomes for the coming month, though I’m wary of it as a tool. It is currently in phase 7/8, I think, which suggests fairly changeable weather but warm weather more likely for the first half of June – the MJO then progresses into no active phase, which suggests something more settled likely.

Hurricane season is expected to be busier than normal, and these can introduce some uncertainty, particularly in August and September – as they have been known to change our previously expected weather patterns into something much cooler and wetter – or much warmer and sunnier.

June

Well we are in day 8 of June as I write, so pointless telling you what I think the first week will be like.

Early changeable conditions will trend towards drier and sunnier weather, tending to be warm or very warm – but with some variation in cloud amounts and temperatures, and the odd shower or weak weather front.

A strong build of high pressure over Europe to our south, with much hotter conditions than normal is likely to effect our weather in two ways for the latter half of June – we will have the opportunity to briefly import some hot conditions for short hot spells (this is uncertain – the heat may stay very close to our south instead), but more likely we will import some thunderstorms or ex-thunderstorms that have become areas of general heavy rain, so some short unsettled spells – though for most of the latter part of June we should be settled, some sunny days, some cloud at times, and more often warm or very warm.

Overall I expect a somewhat warmer than average month, a slightly sunnier than average month, and below-average rainfall – though the latter does depend on avoiding any particularly torrential downpours being imported.

Confidence level around 75%.

July

The more likely start to July would be something similar to how June ended – generally pleasant with decent sunny spells, and temperatures very warm/quite hot. However with the expectation that at times we may import more heat/humidity for short spells from the south – along with some outbreaks of downpours/thunderstorms.

During the middle third, perhaps middle half of July, the more likely outcome sees high pressure develop to our east. Depending on exact positioning of the high pressure and the airmass source, this could lead to some unusually hot weather – I’d suggest this is the period when heatwave conditions are more likely.

However, possible low pressure over France may cut off any source of particular hot air to this set-up, in which case we’d be looking at temperatures close to the mid/high 20’s, and an increased chance of thundery downpours at times.

No particular signal for the latter part of July, though perhaps slightly more likely somewhat fresher conditions with some showers. Very low confidence.

Overall I expect a warmer than average month, a slightly sunnier than average month and rainfall…well…it depends on if we catch any particularly torrential downpours. Around average assuming that we don’t catch anything too crazy in terms of a downpour.

Confidence level around 70% – main uncertainty is positioning of high pressure during that middle third/half of July – too far east and it could be more unsettled than I’m forecasting!

August

August I am a lot less confident about.

Suggestions are that high pressure is more likely to be to our north-east or north at times, with the jetstream more likely pushed south over the UK.

Which would mean low pressure and resulting rain/showers crossing the UK.

However I also think high pressure should at times build over the UK from the south-west, blocking any low pressure invasions for some short spells.

Broadly I’m going to suggest a fairly mixed month – yes some unsettled spells, but also some fine, dry weather at times too – occasionally on the hot side. I don’t have a good enough handle of likely weather patterns to have an idea of what period of August may be more likely to be unsettled, or hot, etc.

Overall I’d suggest a slightly warmer than average month, a somewhat less sunnier than average month and a somewhat wetter than average month.

Confidence level just 30%.

Summary and Autumnal thoughts

So in summary, I do expect a warmer/hotter than normal summer, with the best spell of weather probably broadly from mid-June to late-July, with the highest chance of heatwaves in the middle third/half of July. Though with some heavy showers/thunderstorms at times.

August more mixed with some unsettled spells, but very low confidence.

Autumn? Well, if a weak La Niña is still in play then I’d suggest that a wetter than normal September is more likely than not – though low confidence with the active hurricane season expected, this could easily be pushed north to leave a warmer than normal month.

A mixed October though perhaps drier than average.

An increased chance of colder northerly/north-westerly flows in November, with some frosts and generally fairly dry conditions being more likely.

No particular signals for winter yet.…

Welcome to my weather forecast for Spring 2022.

Let’s hope it is more accurate than my winter forecast. I always suggest that you take these forecasts with a huge pile of salt, but normally the general pattern isn’t a mile away.

My winter summary was – “a slightly drier and colder than normal winter is expected, though with some notable unsettled spells too – especially in January”. It was slightly drier than normal, though it was milder than normal. We did get notable unsettled spells – but not in January! In fact, if you swapped my January and February forecasts around, then my winter forecast would have been half-decent.

So. Take this forecast with a bucket of salt. Often I get quite a bit right, but sometimes I get it badly wrong – like this winter.

Thanks to Jane for the photograph. A donation to the charity of your choice will be made…if you are reading then please drop me a message.

Background Signals

I’m a bit lacking in time at the moment so will be brief.

The stratospheric polar vortex remains very strong for the time of year – well, it did before a very recent warming event up there. Difficult to know whether it will recover, but if it does, then a return to westerly winds will remain likely for early spring. The warming event increases the chances of blocking highs before then – like we have right now, in fact.

La Niña is still going, so will increase the chances of westerly winds during spring, especially the early part – La Niña is fading and may be replaced by El Niño later in the year…we’ll see.

March

March looks like it will be dominated by a battle between a cold blocking high to the east, and low pressure systems trying to push in from a still active Atlantic.

The beginning of the month will often be settled, some days sunny, some days cloudy – though there will also be some days with slow-moving weather fronts stuck, bringing some rain. Generally quite mild, though some overnight frosts also.

Around the middle of the month, or just before, those weather systems to our west will have more success in pushing the block back, so there will be more wind and rain over the period.

For the latter third, we should see high pressure trying to push up from the south, but likely an active jetstream also. Details a bit uncertain, but I’d expect some quite warm spring-like days, and some spells of heavy rain on other days. Overnight frosts less likely, but still very possible.

Overall I expect March to be warmer than average, slightly drier than average and slightly sunnier than average.

Around 75% confidence.

April

April I expect to be dominated by high pressure close to, or over the UK.

April perhaps starting changeable with some occasional rain bands and sunshine/shower days – mixed with some pleasant days. The pleasant days more likely to outnumber showery days towards mid-month – temperatures will depend on exact positioning of high pressure, and some chilly nights could be expected, but hopefully some pleasant days.

Suggestions that for the latter part of April, high pressure is closer to our west, allowing more northerly or north-westerly flows to prevail, which would be cool and cloudy, perhaps with showers.

Overall I expect April to be warmer than average, slightly drier than average and slightly sunnier than average.

Around 70% confidence – main uncertainty being positioning of high pressure.

May

Confidence is lower for May, though high pressure seems likely to be fairly dominant.

However during the first part of March, it looks more likely to be our west, which would again bring a cooler and cloudier flow, with showers or rain at times – though some dry days also.

The middle of May may be some form of transition to something nicer – with the latter part of May more likely to see high pressure either over the UK or to our east, with warm or very warm conditions, and the odd heavy shower, being the more likely pattern.

Overall I expect May to be slightly warmer than average (though with large variations), around average rainfall, and around average sunshine – perhaps slightly below average.

Around 60% confidence. Not much in the way of long-term drivers to affect May, and the timing of the final stratospheric warming will affect when any cooler spell happens.

Summary…and summer thoughts

So, quite a pleasant spring expected. Overall a little warmer and sunnier than normal, and a bit drier than normal. If I get it wrong, I suspect that maybe I’ve underestimated how warm/sunny it will be, rather than the other way around. We shall see.

Early summer thoughts are for a hot June…but becoming increasingly unsettled in July and August – particularly August. Which feels very normal.…

Welcome to my winter 2021/22 weather forecast for Reading and the surrounding areas.

This is going to be quite a long post…I guess I should pour myself a drink…it is nearly Christmas after all.

So let’s start with some admin as usual.

Firstly thanks to Grace for the superb photograph, and first clue to my expectations of the weather this winter. A £20 donation has been made to Blood Cancer UK.

Secondly thanks to everyone who sends in photographs more regularly, comments, shares, etc – you ensure there is still a point in me doing these forecasts.

Finally a reminder that seasonal forecasting is experimental. Though my understanding and the understanding of the general meteorological community improves every year, some parts of this forecast will no doubt be wrong.

I’m actually really happy with my autumn forecast which was surprisingly close to reality – I’m particularly delighted to have picked out the signal for the cold spell at the end of November, 3 months ago. That said, background signals were strong.

Background signals

Which is a good time to start talking about background signals going into this winter.

Unsurprisingly the background signals are conflicting and create quite a lot of uncertainty – arguably more so than usual. Yet there are plenty that point to a colder than normal winter – alas, the seasonal models generated by super-computers point to a mild winter. Which is why you may have heard professional meteorologists arguing different cases.

Of course, nobody knows exactly how it will pan out – some professional and experienced forecasters are going to be wrong. Maybe I will too.

Anyway, those signals:

La Niña. We had a La Niña last winter, and we have another one this winter. La Niña is thought to increase the chance of north-westerly/northerly flows in November/December, and milder westerly flows in January/February – hence why I was pretty confident of the current cold spell some time out.

It does also depend somewhat on the strength, and also where the La Niña is centred – this is more of an east-based La Niña which I believe increases the cold signal for North-West Europe, and can also increase the chance of high pressure forming to our north/north-east – which would suggest cold easterly flows are possible.

Madden-Julian Oscillation. The pattern of thunderstorms over the Indian and Pacific Ocean has an effect on our weather and the pressure patterns. This is more of a medium-term forecasting tool, so really only any use for December. Currently it is in phase 6, and looks like going into phase 7, which should promote high pressure forming to our north/north-east.

However, it is argued that MJO signals are often over-ridden in La Niña winters, so I’m not sure how much notice to take.

Quasi-Biennial Oscillation. These are stratospheric winds which switch from west to east, roughly every 22 months. It has recently switched to east which tends to encourage a weaker polar vortex and increases the chances of cold weather in Europe.

Said polar vortex is kind of disorganised in the troposphere (our level of atmosphere) at the moment, though has hints of organising. In the stratosphere (way above our atmosphere – the next level up) it is unusually strong. If the tropospheric and stratospheric polar vortexes couple, then you can wave goodbye to the chance of cold for weeks – sometimes even until the end of winter – and you’ll have weeks of mild, often wet and windy weather. There are hints this coupling may happen later this month, but is highly uncertain.

One thing that can break the coupling of the vortexes, is a sudden stratospheric warming event (SSW) which you’ll likely have heard me talk about in previous winters. These are a sudden warming of the stratosphere where the winds reverse fairly suddenly. What normally happens 2-4 weeks afterwards, is that high pressure blocking systems set up across the northern hemisphere and cold air floods down into the US, Europe and Asia – though not everywhere, as some places will be on the mild side of the blocking systems.

We had one in 2018 and ended up with the “Beast From The East” – a classic response from an SSW. However we had one last winter, and there was little effect on our weather – we had some cold weather that followed, but nothing unusual and arguably not because of the SSW. However, I do believe that the colder spring that we had was because of the SSW.

It is impossible to know if an SSW will happen more than a couple of weeks ahead. However, a pressure pattern is currently setting up over Europe/Asia that can be a trigger of one, say by late December/early January – so with the lag, that gives a slightly higher than normal chance of significant cold in February.

Finally, the solar cycle. I feel this is more debatable than most signals, but periods of low solar intensity like we are coming out of now, tend to encourage weaker polar vortexes and hence a greater chance of cold spells. And those winters where solar activity is just starting to increase, like this winter, are arguably most likely to experience this effect.

I guess you want a forecast now?

Hopefully you can at least you can see there are lots of conflicting signals, even if more of them do point to cold than normal. As such, overall I think winter will be slightly drier and colder than normal – though with some unsettled spells.

December

December looks like it will be a battle between an Atlantic Ocean finally waking up – and a blocking high stretching from Siberia to Scandinavia.

Generally it will be colder than normal, though low pressure systems will battle into the block, bringing wind and rain at times. There is a plausible chance that there could be some heavy snow as low pressure systems struggle as they come up against cold air to our east – but most precipitation should be rain.

After around mid-month, the jetstream should shift north, with high pressure building from the south – still some weather fronts but mostly light/patchy rain, overnight frosts and fog possible, though generally slightly milder than normal.

Then towards Christmas, that cold weather block to our east looks like it will migrate west, bringing colder air and a seasonal feel, with sharp frosts possible and cold, crisp sunny days. Snow showers would be somewhat possible though dry weather is expected to be dominant.

Overall I expect temperatures to be slightly below-average, rainfall slightly above-average and sunshine amounts around average.

Confidence level 75%. Main uncertainty is over the Christmas period – as it is certainly possible that we retain a milder southerly/south-easterly source and have mild, dry, probably cloudy/foggy weather instead.

January

January does look more unsettled with more influence from the polar vortex. Any early cold and dry weather should be shunted out of the way by a resurgent Atlantic, perhaps initially some snow as the milder air battles to displace the colder air, but generally becoming mildish and wet.

Occasionally the flow should be more north-westerly, allowing for colder weather, though nothing extreme, and brief easterly flows will also be possible – so though rain is the more likely outcome, there will be marginal opportunities for sleet/snow.

Also worth mentioning that the heaviest rain should often be to our north, so I’m not expecting the wettest month ever, but generally fairly unsettled with some short dry spells.

Overall I expect temperatures to be slightly above-average, rainfall somewhat above-average and sunshine amounts slightly below-average.

Confidence level 65%. Main uncertainty is the block to the east, and whether colder and drier weather could again spread west at times.

February

February currently looks likely to be a dry month with high pressure generally over the UK, or close to.

This does lead to some uncertainty on temperatures, arguably something milder/cloudier is slightly more likely early February, with colder than normal conditions most of the time after early February.

Often sunny though a risk of fog at times, regular overnight frosts likely which could be sharp, depending on the exact position of high pressure.

Rainfall will be limited, though occasionally the odd weather front will pass over bringing a bit of rain, perhaps sleet/snow, as the high pressure repositions itself.

Low confidence but there are suggestions of a very mild end to February being possible.

Overall I expect slightly below-average temperatures, below average rainfall and above average sunshine.

Confidence level 60%. Main uncertainty is the chance of an SSW, which would increase the chance of easterly flows and snow showers – I’ve assumed no SSW in the forecast as they are impossible to predict this far out.

Summary and Spring Thoughts

So, overall a slightly drier and colder than normal winter is expected, though with some notable unsettled spells too – especially in January.

Remember, it will be a shock if all this comes to pass, but hopefully it will be a good enough guide. Should an SSW occur, then there will be a good chance of a significant cold spell 2-4 weeks later, but it is impossible to know now.

Assuming no SSW (or an SSW that doesn’t favour cold in the UK), then early signs are that March could be warmer than normal.

However, don’t get too excited – early hints for April and May are for colder and somewhat wetter conditions than normal.

Well, I hope you enjoyed reading this forecast, I hope it is reasonably accurate and I hope you can enjoy the weather – whatever it throws at us.…

Autumn is here and so is my Autumn 2021 Weather Forecast.

Seasonal forecasts are experimental and things go wrong. My summer forecast accuracy was mixed at best – so do take this as a guide more than an actual forecast. Hopefully more will be right than wrong.

Was more right than wrong for my summer forecast? Hmmm. In terms of weather patterns, for example high pressure being dominant in August, then I’m happy with it. Alas, I had assumed it would be a sunny high as most high pressure systems are in summer – we’ve been really unlucky with the wind direction and hence all the cloud. So, though I may have predicted high pressure to be dominant – I also predicted it would be mostly sunny too. Is that wrong? Half-right?

Same with June and July, though I again feel that the main patterns were reasonably accurate, I vastly underestimated rainfall in June – I totally didn’t expect weak low pressure after weak low pressure to trundle across and set up over south-east England. I don’t think anyone did.

So don’t take this forecast as gospel.

Please can you also share the forecast in some way. Invite friends on Facebook, retweet on Twitter, e-mail it to your boss. Whatever works. Or don’t share it, I’m not fussed.

Finally thanks to Eve for the photograph. Please get in touch so I can make the charity donation!

Background signals

La Niña. This is expected to develop again over autumn, which tends to promote unsettled conditions in September and settled conditions later in autumn.

Polar vortex. Every August the polar vortex starts to develop – a weaker vortex is more likely this autumn/winter, similar to last year, this increases the chance of “stuck” weather patterns, and reduces the chances of weeks of low pressure systems going west to east on a strong jetstream, like we can often have in autumn.

Hurricane season. This is a curveball rather than a signal, but I do expect a busy September for Atlantic hurricanes and they can significantly alter expected weather patterns. This does make September especially difficult to forecast.

September

September is a difficult month to predict. It starts dry, and likely becomes very warm/quite hot, though after a couple of hot days thundery downpours may develop. After around 9th, things get tricky. A changeable two or so weeks is the more likely outcome, with some warm sunny days, some cooler cloudier days, some showery/wet days – probably warmer than normal.

However, if we strike it lucky with an Atlantic hurricane curving up and way north of the UK, it could reinforce the previous change to very warm/quite hot conditions – and we could end up with a mostly very warm and sunny middle of the month. This is an unknown curveball.

Towards the end of the month, a change to more settled conditions (assuming we had a changeable two weeks) is the more likely outcome, with temperatures around normal.

Overall I expect above average temperatures, around average sunshine, slightly below average rainfall.

Confidence level of 40%. Which is unusually low.

October

There are fairly strong signals of high pressure being close to our east for the start of October, which should translate to warmer and sunnier than normal.

A change to more unsettled conditions is likely after the first 7-10 days, with spells of wind and rain, temperatures around normal.

Low confidence by the end of the month, I’d suggest broadly changeable, some wind and rain, some drier spells. A very slight signal for colder north-westerly/northerly flows being more likely.

Overall I expect slightly above-average temperatures, slightly below-average sunshine, around average rainfall.

60% confidence.

November

Again no real signal for the beginning of November, I’d assume fairly mixed, some rain but nothing too much, more dry conditions with variable amounts of cloud. Probably on the mild side.

There is a stronger signal from around mid-month, maybe a bit earlier, for high pressure to build to our west, allowing colder north-westerly or northerly flows, with some showers at times, and a mixture of sunny and cloudy spells otherwise.

Any showers more likely of rain down here, but wintry showers will be possible in any more potent northerly. Overnight frosts more likely too.

Overall I expect slightly above-average temperatures (though colder than average later in the month), around average sunshine amounts, somewhat below average rainfall.

Summary and Winter Thoughts

So, if I’m reasonably on target, we should have a warmer/milder autumn than normal though with the second half of November more likely to be colder than normal. A bit drier than normal overall, though some wet spells. Sunshine amounts around normal.

Background signals are mixed for winter – nothing new there. La Niña would tend to suggest a wetter winter, assuming it develops to be quite strong as expected (weaker La Niña’s are more supportive of cold weather) – yet there are plenty of background signals that suggest that cold spells are more likely than normal too. Kind of contradictory.

On balance, I’d say a colder than normal start to winter, ie late November and into December is more likely.

A mixed January.

A wet and windy February.

Winter always has the wild card of sudden stratospheric warming events, roughly every other winter. We had one last winter and it did bring some cold northerly weather at times, albeit minimal snow. Impossible to predict the chance of one occurring this far in advance.

That’ll do. I need some dinner.…

Welcome to my Spring Weather Forecast 2021.

Spring is my favourite season – especially late spring and early summer when it is often very warm but not too hot, and there are chances of thundery downpours – my favourite kind of weather day.

It is, of course, still early days for spring and still rather chilly as I write – but at least there is blossom on some trees, daffodils are starting to shine – the hope that spring brings never tires, and after arguably the most difficult winter collectively for decades, it is nice to just see the beginnings of spring.

I’m actually quite happy with my winter weather forecast – these seasonal forecasts will never be perfect but I thought I did a good job. We had more cold spells than recent winters and though we didn’t quite get something like February 2018 – the models teased that could happen, the sudden stratospheric warming event happened but just didn’t split the polar vortex which is likely why we didn’t quite have that newsworthy cold spell that we would have referred to for years to come.

So as I mentioned, these seasonal forecasts are experimental – I will not get everything right. Think of them more as a general guide, my hope is to get more right than wrong. I am not a professional meteorologist.

As always, I’d kindly ask you to share this forecast in some way – I don’t ask for anything other than a quarterly share/retweet or whatever your preferred action is.

And the final bit of administration is to say thank you to Eve for this classic Reading in spring photograph. A donation has been made to British Lung Foundation.

Background signals

I think background signals are less useful in spring than they are in winter, but those of note include La Niña which is weak and trending towards neutral – though there is some uncertainty as to whether it may strengthen once more May onwards – one would assume the trend to neutral continues, but some models have suggested La Niña could strengthen which would increase chances of rain/showers come summer.

In the more short-medium term, the MJO is suggested that it may go into phase 8/1, which would support the idea of high pressure to our north (ish) later in March.

The sudden stratospheric warming event from January will likely still have some impact – I believe that it increases the prevalence of blocking highs through spring, and there is more cold air at mid-latitudes because of the SSW that could be tapped into during early spring.

Finally, the polar vortex is strengthening which should encourage the jetstream to head further north – taking low pressure systems with it, especially as the influence of the SSW fades.

So quite a mixed and conflicting set of background signals as always, but there is a theme and that is of high pressure being close to the UK more than normal – so a drier and sunnier spring than normal is expected. Getting the position of the high pressure systems – and hence the source of the air and subsequent temperatures is the challenge.

March

March starts dry and mild. Towards the first weekend colder weather will spread down from the north – nothing especially cold but still cold enough with overnight frosts – a chance of a light wintry shower.

For the second week this will be replaced by more unsettled conditions with spells of wind and rain, and showers in between – temperatures average or a little below. I wouldn’t rule out sleet or snow either in any more notable north-westerlies.

That unsettled spell should be short-lived and high pressure should take back over for the rest of March – positioning uncertain at the moment and it will vary a bit. When it is closer to the UK, it will be rather pleasant, mild and sunny – when further west it will be cooler, perhaps colder with showers – a 2-3 day northerly plunge with wintry showers could easily occur. I do think high pressure will be to our west or close to our west for more of this period.

Overall I expect slightly above-average sunshine, somewhat below-average rainfall and slightly below-average temperatures.

Confidence level of 80% – main issue is where high pressure sets up for the second half of March.

April

Again April looks likely to be dominated by high pressure – again there are questions over positioning.

The first half looks more likely to be fairly mixed – there is a signal for both warm southerly winds and cold northerly winds – both involve high pressure close by, so we should end up with interchanging cold/warm spells, with some heavy showers around but more emphasis on sunshine.

Later in April, there are suggestions of high pressure migrating west/north a bit, allowing a cooler and somewhat cloudier north-westerly flow to become more dominant – some showers again but more emphasis on dry conditions overall. Again high pressure position probably varying so some short warm spells could easily be mixed into the dominant cooler, cloudier pattern through this spell.

Overall I expect average sunshine, somewhat below-average rainfall, average temperatures.

Confidence level of 70% – again the positioning of high pressure systems is the tricky thing to capture, and possible that it may be a bit warmer at times than I’m forecasting.

May

Again May will see high pressure over or close to the UK for much of the month – and by May there will be less cold air around to tap into so it should be warmer than average for most of the month.

The first half should be warm and sunny for most of the time – some variations, the odd weak weather front may cross from the north-west bringing some light rain and cooler conditions as high pressure moves around a bit – there may be some dull and cloudy days mixed in too depending on wind direction, but generally the theme will be warm and sunny.

Later in May, low pressure to the south will increase the chance of heavy showers and thunderstorms developing – though it likely remains warm or very warm and sunny most days, some days will see those heavy showers or thunderstorms later in the day.

Overall I expect above-average sunshine, below-average rainfall (unless you get a particularly torrential downpour in the latter part of May) and above-average temperatures.

Confidence level of 75% – again high pressure positioning is the tricky part and certainly possible I’ve over-egged the warmth.

And summer?

Well, that will depend on how La Niña pans out.

Early suggestions are that June will be sunnier and warmer than average – but some unsettled spells too.

There are signals that July and August will be fairly changeable with more rain and showers than normal – and temperatures generally suppressed for summer – though with short heatwaves likely.

Summer is a long way away though, and there is plenty of time for these signals to change.

So your overall take from this should be a drier than normal spring, a sunnier than normal spring, a colder than normal March, mixed temperatures April and warmer than normal May.

Roll on the first weekend where I can sit in the garden and have a beer.

Don’t forget to share!…