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

[WYorksWeather]

Intro

Inspired by the recent revival of the 40C thread, this is probably the next major milestone. There were suggestions of 41C/105F on the other thread, but that's not much of a milestone given we've already reached 40C/104F, and 45C/113F feels like a huge jump, to the point that it might well be a very long wait for anyone to be proven right or wrong! Hence, I settled on this as something of a middle ground.

The question

Question as in the title. A few things worth considering:

• Is 110F physically possible now, if you construct the ideal scenario?
• If yes, how likely is it?
• How will the chance evolve over time?
• On balance, when do you expect to see 110F to be reached for the first time, or will it not happen at all this century?

My answer

My answers in short to the above are yes, very unlikely (far less than 1% per year, but probably above 0.1% per year), I expect the chance to increase quite rapidly in the coming years, and I expect 110F to be reached for the first time between 2040 and 2060. If I had to put a specific year on it I'll say 2045.

[BlueSkies_do_I_see]

On 14 July 2022, the BBC Weather app had the following forecasts showing for London Heathrow

Monday 18 July Max 41C/ Min 23C

Tues 19 July Max 40C / Min 19C

Netweather.tv also posted this to Facebook, temps in Eastern England of 43C

https://www.facebook.com/share/thk8VMZV1hHrcRoh/

I personally think 41C will be reached by 2030 and possibly 42C. 

As a lifelong Midlander, the last few summers have felt too hot for me. In the future I will be checking the weather app and heading to a coastline that is cooler, usually that's Northumberland.

 

 

Edited March 12 by BlueSkies_do_I_see

[LetItSnow!]

I don't think it's even that rare a chance. 2019, 2020, 2022 all saw intense heat spikes and 2023 had an exceptional spell that just happened to occur outside of the peak time. All it takes is another waft of hot air remaining in place for a day or so longer and preferably occuring in July or early August and we'll do it. I would be very surprised if we haven't at least attempted it around the 40-41C mark by 2029. Every year the contintent is burning up with every year since at least 2015 having mass expansions of heat burst northward and I'm sure 2024 will be the same. As long as Europe keeps getting hotter and dryer then it's highly likely we'll get there soon, unless we have a spell of relatively cool summers. I hope the latter, but I've grown to expect wisely.

[BlueSkies_do_I_see]

 LetItSnow! Would an exceptionally wet spring reduce the chances of a raging hot summer?

(Not that I want a wet spring!)

[LetItSnow!]

 BlueSkies_do_I_see Wet soil isn't as conducive to heat (or cold) so if the spring and even June were wet it would perhaps limit potential, but 20-25C uppers are going to be baking hot regardless. It may just mean the difference between 39C and 43C. But each heatwave is so unique in its set up with so many different factors.

Wet springs are lovely and good for gardens. I enjoyed last years very much so. I do think that a wet spring would probably be overkill this year though. I just hope we don't go from one extreme to another...

[raz.org.rain]

Do people still use Fahrenheit? Anyways, I'd say it is a possibility. It's likely the next benchmark we'll reach over the next few years. We came somewhat close to reaching it in 2022, and supposedly it's not the first time we've come close either. As ridiculous as it sounds, I reckon we'll see 45°c before 2030.

[Wold Topper]

 raz.org.rain you are correct about one thing... 'it does sound ridiculous' 45°c within the next 6/7 years.... give over

[TheOgre]

I’m going to say not yet but later in the century.

We’ve only nudged 40C once and we’ve never had a 39C. It's difficult to know whether it was a trend setter or just a one off for now.

It took 19 years to jump from 38C to 40C so perhaps 20 to 35 years to jump from 40C to 43C?

[LetItSnow!]

 TheOgre But it in the space of three years we challenged it multiple times and it has been said that contributing factors that had they been only slightly different would have reached a higher figure. I’m genuinely surprised why some people think it will be a long time to heat it. Bear in mind warming will accelerate the chances, so that 20 years gap may only become 10, maybe even 5. I really hope not but I would have expected 41-43 by 2034. I pray to be wrong.  

[Scuba steve]

I doubt it that’s Joshua Tree NP level temps , a huge  landmass and a lower sun restricting insolation  here imo

[Catherine91]

By the end of the century, I'd say very likely!

[kold weather]

I'd guess 43c is probably at the very very top end of what is in theory possible here, it would require just about perfection in every single element. Even in a world around the 1.5c mark I still think that maybe too far.

 

[Wade]

 kold weather I would say the high 40's would be at the very very top end of what is possible. 43C is more than possible if the synoptics are right, it was quite a short burst of heat in that spell in 2022 if I remember right so could you imagine what we could've got if the heatwave lasted longer. The fact a couple of runs albeit extreme showed the possibility of 44C tells you something, if the world carries on like this, we are in for a bad time.

Edited March 13 by Wade

[cheeky_monkey]

its strange to think that in reality 43c in Edmonton Alberta should be more likely than the UK...however the hottest temperature ever recorded here is 37.2c back in 1937 

[In Absence of True Seasons]

 cheeky_monkey In theory, yes. Interestingly, other parts of Western Canada have records that quite far exceed Edmonton's. I know Kelowna has recorded 45c for example.

 Wade It was a fairly short heat "blast' but that summer (and spring) had been very warm, dry and sunny overall so the synoptics were well-set for any serious heat to quickly manifest as and when it landed. 

In my area at least, we were getting 20c+ sunny days from late March onwards. 

[cheeky_monkey]

 In Absence of True Seasons Kelowna is well known as heat trap sandwiched in the Rocky Mountains 

[Wade]

 In Absence of True Seasons Given how much rain, dampness and greyness there has been this last 6 months or so, 40 degrees this summer I'd say is very unlikely.

[kold weather]

 Wade Interestingly in terms of extreme heatwaves it was one of the more sustained ones, hence why we absolutely obliterated the mins, because often the central core of the plume is already getting ejected eastwards by the time it gets to the UK, hence why we might sneak to 36-38c and then see a line of storms come in to clear it out.

On 18-`19th the plume was big enough that when the push eastward did happen it took quite some time to eject out of the way, so much that the plume lasted throughout the night and took towards the back half of the 19th to get replaced, by which time eastern parts had been under the extreme air for 36hrs.

I'm not saying that it was the perfect plume, but I do think it was well into the top 0.1% of what is possible given just how extreme the break was in the CET. Even if you take out CC warming of about 1.2c, it still would have obliterated the old UK/CET mean. The max record would have been a smaller jump mind you.

Still for it to be 2.8c warmer than the next warmest day by CET is exceptional, and thats a record going 350 years strong. Even removing the CC impact, thats still over 1.5c warmer than the previous, still by far the biggest jump up to the next warmest recording.

[In Absence of True Seasons]

 Wade My thoughts exactly. We would have to get an exceptional April, May and June in terms of warmth, dryness and sunshine to make it a possibility IMO. 

That's not to see we won't get the mid 30c's heatwave in July/August, we probably will, but there's a big difference between that, and the summer we had in 2022 where most of July and much of August in London was effectively like being transported to Barcelona for 6 / 7 weeks.

[WYorksWeather]

Quite a few points made here - not going to respond to them all individually as there's too many, but a bit of a summary.

I think the key more so necessarily than the weather patterns in March/April is more what happens in May/June. We could have a very wet March and April, but that water then just runs into the rivers as the ground is saturated. It then only takes a very warm May followed by a hot June to dry out the ground. That would then provide ample setup for any extreme heat plumes in July or August to reach their maximum potential.

In terms of some of the more extreme mentions about temperatures, I don't think 45C or higher is possible at the moment, simply because of the lack of such temperature records in our immediate neighbours in continental Europe. Germany has no reliable record in the 42s, and most of north/central France is no higher than 42-43C.

For the overall setup for a 43C or higher temperature, here is the scenario I think we would need at the moment (obviously 20-30 years down the line, it needn't be as extreme). We would need a very warm and/or hot May and June to dry out the ground sufficiently. Then, we would need a record breaking European heatwave, sending the temperature above 50C in southern Spain or Italy. We would then need to tap into an element of that, with a Coningsby style plume, at the absolute hottest time of year so probably 10 days later than Coningsby was, and the arrival of the hottest 850hPa temperatures would need to coincide with morning or lunchtime, and they'd need to be perhaps 28C or higher. It is barely, just barely physically possible I think. But in practice, the number of things that would have to be set up right is such that it'd be an absolute fluke. The more I think about it the more I err on the side of closer to 0.1% chance per year rather than 1% per year.

But, to be fair, the same could have been said about a 40C heatwave in 1990, when we had only just recorded our first 37C. And 30 years later, it happened. If the same were to be true again, that would lead towards mid-century as the time when we might see it. If the trend did hold, then 45C or above wouldn't become possible until 2070 or later. Of course we might hope that the situation has changed by then such that this sort of extrapolation doesn't hold!

[hillbilly]

I never thought we would see 40 deg in this country but i have tried to eat my hat.However lets not forget this could have just been a perfect set up the likes our children may never see however unlikely and also not forgetting many records set in August 1990 were not broken until 2015 and in 2022,that is 30 years!

 

[Alderc 2.0]

I would say it’s certainly possible. The fact the numerical models from both GFS and ECM indicated 43-45C was possible back in July 2022 i don’t see why it’s remember. Also remember although it has a continental climate Lytton in Canada has a latitude similar to the south coast and they reached 49.6C

[MattStoke]

I think it's possible. There were model runs in the lead up to the 40'C spell that showed 43-44'C quite widely because they had the peak of the hot airmass over the UK during the afternoon. In the end, the peak of that hot airmass actually occurred on the Monday night.

[MattStoke]

 kold weather Worth noting, a 1.2'C rise in average global temperatures (Actually about 2'C for the UK and mainland Europe) doesn't mean locally extreme hot spells are automatically 1.2'C higher than they would have been. The effect on extremes is greater than that.

Climate change also makes such events occur more likely to occur more frequently. It alters the actual weather synoptics, pressure patterns etc. Not just absolute temperature.

Edited March 14 by MattStoke

[Daniel*]

No, I categorically do not think this is possible on current climate might that change by 2100? Possibly. The main challenge is latitude and surrounding by relatively much cooler water. Realistically it would only happen in SE or EA. I feel example of Lytton, BC is given as reinventing what’s possible but there’s not a single site with similar geography to that in UK. There is not an exceptional foehn site in southern UK. The most notable foehn sites are seen in Scotland but of course it’s never going to be be as hot up there.

Edited March 14 by Daniel*