Heatwave to start, mixed (and somewhat uncertainly so) after.

Thanks to Pauline for the photograph.

Starting with the general picture which sees high pressure across most of western and central Europe, with some very hot air spreading across much of the continent – I believe 46’C was recorded in Spain yesterday, a new June record. Low pressure systems either well to the north of the UK, or the west.

Sunday starts cloudy. Gradually the sun will break through, to leave long spells of sunshine in the afternoon. Hot, around 30’C, give or take, depending on how quickly the sun breaks through the cloud. Mostly clear skies overnight and a fairly warm night, down to around 18’C.

Monday sees long spells of hot sunshine all day. A little bit of cloud may bubble up in the afternoon. Hotter than it has been, with the upper layers of air being unusually warm, 32’C should be reached, a small chance of 34’C. A warm night in mostly clear skies, around 19’C.

The heat hangs on for Tuesday, again long spells of sunshine though more in the way of high cloud making it hazy at times. A very small chance of a thundery downpour developing in the afternoon, like a 2% chance. Hot, perhaps very hot – 32’C again should be reached, though I wouldn’t yet rule out anything up to 36’C. Some cloud and perhaps a shower overnight, and warm once more – no lower than around 19’C.

Things become very uncertain for Wednesday. Low pressure probably develops over France, so let’s assume it does for now. But even in this assumption, maybe we have a little bit of showery rain, maybe we have some intense thundery downpours, maybe something in between – or maybe it all stays in the continent and we have hazy sunshine. I don’t think a forecast for Wednesday will be clear until the day before.

What I am more confident on is that the heat will move away (even if the French low doesn’t develop), so temperatures somewhere between 21’C and 27’C, depending on cloud/sunshine/rain developments.

By Thursday, we probably see a ridge of high pressure building again, though a more north-westerly flow.

Which would mean broadly speaking, sunny spells, some cloud, a small chance of a shower – around 22’C to 25’C. Though given Wednesday’s uncertainty, I cannot say I am especially confident for Thursday yet.

Friday will probably be sunny and dry, with some bits of cloud. Very warm, around 25’C.

Current suggestions for next weekend are for low pressure to move down from the north-west, so a cloudier weekend with showers or showery rain at times. Still probably on the warm side.

Again, not especially high confidence though.

The more likely outcome for the week after is for somewhat more mixed conditions, generally warm but nothing unusual likely, often dry, sometimes quite cloudy, sometimes sunny, some showers on some days.

Have a pleasant Sunday, if I get chance to update on Wednesday’s uncertain forecast beforehand I will do, but I might not get time. So otherwise the next forecast should be on Thursday morning.