And welcome to the rather delayed Autumn 2024 seasonal weather forecast for Reading & Berkshire – though it should broadly apply to much of southern England.

Let’s start with the usual caveat – seasonal forecasting is experimental, some of this forecast will be wrong. It is my best attempt at using background signals, long-range models, current patterns, and, well, vibes to establish a more likely route through the next 3 months.

Unexpected events can and do happen, and then throw off course the forecast.

Thanks also to Paul for the stunning photograph – a charity donation will be made to MS Society. Thanks to everyone who sent them in, and also to those sending them in for the usual twice-weekly posts – the forecast would be a lot more boring without them!

Background Signals

We are probably transitioning back into La Niña conditions, which would increase the chance of cooler north-westerly flows later in autumn.

The remnants of hurricanes can change our weather patterns when they recurve into the Atlantic, which adds uncertainly for September and to a lesser extent, October.

However the intertropical convergence zone has been further north than usual, which is thought to be hindering tropical storm development. I have no idea if this will continue.

Other than that, nothing really stands out as a background signal.

September

Well, September did start warm and unsettled, then went much cooler. That’s obviously not a forecast as I’m writing this on 12th September!

Warmer weather will quickly re-establish itself, with high pressure likely to build close to the north – allowing a warm easterly to develop. Sunshine amounts should be higher than normal, though some overnight low cloud feels likely on some days, which could take a while to clear.

Likewise in the final third of the month, low pressure may well develop to our south over Europe, with a chance of showers/thunderstorms moving north towards us at times.

Lower confidence by the end of the month, but something more unsettled and somewhat autumnal is more likely.

Overall rainfall amounts somewhat higher than average, sunshine amounts around average, temperatures somewhat higher than average.

Confidence level around 60%.

October

October looks likely to have quite a notable westerly flow. Possibly starting unsettled though more likely I think low pressure will become centred to the north of the UK, so we’ll tend to be dry much of the time in the south, relatively mild, sometimes sunny, perhaps even the odd warm day. Then occasional weather fronts bringing a bit of rain every 2/3/4 days – that kind of broad pattern. Windy at times.

Later in October, the more likely outcome seems to be that low pressure will be tracking further south, so areas of rain more frequent, heavier and more persistent, windy also – but still there should be some dry days too.

Overall rainfall amounts around average, sunshine amounts around average, temperatures slightly higher than average.

Confidence level around 50%.

November

During November, I expect the jetstream to be pushed further south, bringing some wet and windy/very windy conditions at first in November, but also a chance of some colder weather in between areas of rain.

In the latter half of November, more likely the jetstream is to our south and we see broadly drier, sunnier and colder weather – northerly (ish) flows more likely than normal, overnight frosts and perhaps wintry showers.

Overall rainfall amounts around average, sunshine amounts around average and temperatures slightly below average.

Confidence level around 50%.

Summary And Early Winter Thoughts

So a pretty mixed autumn – some wet spells but also some notably sunny periods too. I’m not foreseeing a constant washout of an autumn.

I’ve probably rushed the research of this compared to normal, so I’m a bit less confident, plus background signals seem pretty weak, but it will do for now.

Maybe in a few years, the AI models which are giving me increased confidence in the 7-10 day range, will be able to help with longer range forecasting…will be interesting!

Early winter thoughts are for a drier than normal winter – temperatures very dependent on positioning of high pressure systems, but assuming La Niña does develop, then cold spells very possible in December, a milder trend more likely in January/February but cold snaps still possible…of course, it is winter.

Full daily forecast tomorrow.