Is 110F (43C) possible in the UK?

[Metwatch]

Agree with Dan above, 43C I would say is still not possible in today's climate, but in 50-60 years time it might just be within the realms of possibility. Majority of central and northern France haven't even seen 43C yet, most places seem to be in the 40-42C area. Parts of Spain the same, Madrid the record is around 42C, though it is at like 650m elevation, but same for other cities north of there. 43C is only about 4C away from Spain's all time record, so it would be truly incredible for the UK to get it. Until Spain hits 49-50C, and central / northern France reaches widely 42-43C, I can't see the UK reaching 43C.

As of 2024, the limit in the UK i'd go for is the 41-41.5C area, 2022 got very close to the ceiling with current climate, and I think if the warmer air coinicided with early to mid afternoon, then 41-41.5C may have been reached, which is the true ceiling of what is possible at the moment.

Always the small chance of another 40C this year, no one knows, but I'll go for a fairly "non-scientific" prediction and say we'll need to wait at least another 10-15 years until 40C is seen again. 38-39C should be seen one to a few more times between now and 2040.

Edited March 14 by Metwatch

[kold weather]

Yeah can only agree with the others, most countries yhe other side of the channel only manage somewhere between 40-42c. Paris is nearly there but still a hair short, and all those places don't have a modest moderating impact the channel has.

I can probably make a theoretical claim to it making 43c locally in the UK, but it'd need such perfection at the moment its more or less impossible (probably 1 on a 1000 year type event at the moment I'd guess?)

[I remember Atlantic 252]

Plumes generally do not last long enough, not that I want 43C, no way! everyone wants summer but a decent late 20's will do

[MattStoke]

I don’t understand how people can say 43°C is currently impossible. Slightly different timing on the 18th-19th July 2022 spell would have seen 43°C hit. The peak of the hot air occurred overnight instead of early to mid afternoon. 850hpa temperatures in that overnight period were a good few degrees higher than those that brought the 40°C temperatures.

Edited March 14 by MattStoke

[Metwatch]

15 minutes ago, MattStoke said:

850hpa temperatures in that overnight period were a good few degrees higher than those that brought the 40°C temperatures.

Doesn't mean that difference would directly translate to the surface.

The clue is in the temperatures recorded in western France the day before under the hottest airmass. Can see mainly 40-42C, no 43C there, and that's without having the airmass to cross the channel and travel further north. With that in mind the limit for somewhere in England with optimal timing of the airmass and strongest solar heating would be about 41-41.5C.

4 minutes ago, MattStoke said:

Peak the hot airmass over France also occurred overnight.

Not really, stayed over the Biscay Bay then slowly advected to land through the 18th, 25-26C. The cooler part of the northern Biscay bay moderated it as well a little.

Edited March 14 by Metwatch

[MattStoke]

 Metwatch Peak the hot airmass over France also occurred overnight. 

Model runs that had that different timing with the airmass showed 43°C was possible.

Edited March 14 by MattStoke

[kold weather]

 MattStoke thing is if it timed later the day before would have been cooler, the night mins cooler due to the lower daytime temperature from the day before which would probably mean that whilst the warming the next day would have been higher itd start from a lower base which probably levels out at the surface.

there is a theoretical max that an airmass can support regardless of timings afterall. How close we were to that is up for debate.

[WYorksWeather]

I think the key really revolves around the meaning of the word possible, which I deliberately left open to interpretation. I don't think the Coningsby event could have led to 43C just by changing the time of day - so in that sense I agree with @Metwatch. Where I disagree is that this therefore means that 43C is not physically possible at the moment. I think it is, but only just. You'd need to stack the deck even more. Move the heatwave 10 days later and that might add half a degree or a degree. Then just make it fractionally more intense - an extra 1C or so at 850hPa, and that probably gets you there.

The question then is how likely is that? Based on recent trends it's probably unlikely that reaching 40C was less than a 1 in 100 chance per year, because if it were we wouldn't have expected the number of recent summers that have exceeded 38C - in short, although it broke the record, it didn't break it by such a large margin that we can just write it off as an absolute fluke. On the other hand, it can't be an extremely likely event in the current climate, on the order of 1 in 10 years or something, because we'd have seen it already.

If we err on the conservative side, let's say 1 in 50 years. I think that still then allows that an extremely fluky event could exceed it by quite a lot. A UK answer to the PNW heatwave, which is often quoted at a 1 in several hundred or even 1 in several thousand year event, would therefore almost certainly be around 43C. I think a lot then rides on how you define possible. The combination of factors is very, very unlikely. But I see no physical reason why it literally couldn't happen, in the context of a western European heatwave of a similarly unprecedented nature to the PNW heatwave.

As I stated before though, I think the odds presently would be far less than 1 in 100, likely closer to 1 in 1000. Hence why I don't expect it to happen before mid-century, when the odds will have risen substantially.