Wednesday 12th August 2026

Heatwave number 5 (I think?!) is upon us, peaking on Thursday – though quite a bit of uncertainty after Friday, including a chance (chance!) of showers.

I got one of my statistics wrong in the previous forecast – where I said “This week will see the 30th day of 30’C or higher in London this year – the previous record was just 20 days in a year (this probably applies to Reading also, give or take, but the statistic I read was about London).”.

The record is actually 34 days, though we will beat that this week.

I’m struggling to find out what the actually statistic I meant to quote was, perhaps you can replace the 30’C with 32’C in that statistics, but…hmmm…I cannot find the original. So…apologies.

Thanks to Greg for the photograph.

So the general picture sees high pressure to our east, dragging up the very hot air – though low pressure to our north-west moving east will start nudging it out of the way from Friday.

Today sees long spells of sunshine all day, very little cloud and hot – reaching around 32’C, maybe a 33’C. Clear skies overnight, and a fairly warm night, getting down to around 18’C.

Thursday sees the peak of the heat. Long spells of sunshine all day and very little cloud – very hot but how so is still a bit uncertain. 36’C feels the more likely maximum to me, though a maximum anywhere between 35’C and 38’C is possible. Clear skies overnight and a warm night, eventually down to around 20’C.

Friday will still be hot but we are past the peak, long spells of sunshine again though a little bit of cloud around, more so in the afternoon. I cannot totally rule out a shower, say 3% chance. Hot, reaching around 31’C. Some cloud around overnight and another warm night, gradually getting down to around 19’C – an outside chance of a shower but barely worth mentioning.

By Saturday we have fresher air spreading down from the north, and a weak thundery low developing over the continent which adds a bit of uncertainty.

Details on Saturday are therefore a bit vague, but probably quite a lot of cloud around for the first half of the day, if not longer. Sunshine more likely later in the day. Still warm, temperatures somewhere between 24’C and 27’C. A very small chance of a thundery downpour later in the afternoon – if they do break out than I think they’ll be much further south-east, say Kent, but still something to keep an eye on. Clear skies overnight and much fresher, down to around 12’C.

Sunday then sees sunny spells and fair-weather cloud, warm, around 24’C. Clear (ish) skies overnight, down to around 12’C.

More uncertainty into Monday, as it does look like low pressure will form to our west, though still a bit tentative – if it does then still open to question as to whether any rain gets this far south.

But on balance, the slightly more likely outcome is for a band of rain to cross either later on Monday or overnight.

After that, showers are more likely than they have been for the rest of next week and probably into the weekend after. With temperatures subdued to around 21’C to 25’C.

I still feel a bit nervous forecasting showers/rain given the way the summer has gone, but this is the strongest signal for a while and one that has been there for this period for a couple of weeks now.

Probably we go hot and sunny again before the end of August, though with some variability and showers/thunderstorms being possible on some days. Still confident of September being warmer, sunnier and drier than normal.

Next forecast should be Sunday morning though if I get time I’ll update on Saturday’s forecast when it gets clearer.