Will we ever reach 40c in the UK

[Wade]

 Metwatch The way things are going, 41 shockingly to many is probs a bit too low, I'd bank on something like 43 degrees in that timeframe given the perfect or worst (depending how you see it) synoptic possible

Edited March 11 by Wade

[*Stormforce~beka*]

This just gave me a good laugh lol

[Derecho]

On 15/06/2013 at 20:10, cooling climate said:

 

As far as 40c being reached on the UK mainland then like SB has said the  preceding

spring would have to be very warm and dry across central and southern Europe with a

very warm Med. You would then need a long dry hot summer here accompanied by

some exceptional synoptics around end of July into early August to even come close to

achieving a temperature this high.

Personally speaking with the UK at a latitude of between 50 and 60 degrees north it is far

easier to break cold record temperatures than warm ones and in a cooling climate (no pun

intended ) this will be a growing trend.

This post aged like milk

Edited March 12 by Derecho

[raz.org.rain]

 Derecho "cooling climate", says a lot.

On 05/06/2013 at 18:12, Eugene said:

 

Of course we will at some point in the UK's history, you didn't put a timeline, 40C has unofficially been recorded before in the 19th century but before reliable screening so not recognised, i'm sure it has before and it will again, just knowing when is the problem.

 

I'm curious, what does this refer to? Has there been an unofficial 40°c in the past?

[Derecho]

22 hours ago, Wade said:

The way things are going, 41 shockingly to many is probs a bit too low, I'd bank on something like 43 degrees in that timeframe given the perfect or worst (depending how you see it) synoptic possible

We saw with July 2022 we don't even need heat in place for that long. If we get a scenario where it does linger in place I could see 43C possible in the SE or Cambridgeshire though like 2022 a prolonged period of drier weather in the months beforehand is a huge help.

[LetItSnow!]

 raz.org.rain I believe there was an unofficial reading of 40C+ in July 1808.

 Derecho What makes it so funny and ironic is that the increasing cold anomalies they spoke of effectively ended the following month as we've generally been mostly very mild/warm since July 2013.

[Derecho]

 raz.org.rain July 1808 had a particularly hot day with some interesting reports from the heatwave that month. Apparently Hull recorded 34C, Suffolk 37C and there was a historic hailstorm in SW England that did huge damage. 

1808 United Kingdom heatwave - Wikipedia

EN.WIKIPEDIA.ORG

Though the exposures of thermometers at this time and hyperbole in weather diaries means some information back then may not be so reliable...

[Methuselah]

 LetItSnow! That was either down to 'encroachment' or, as Donald Trump might say, due to the USAF's jet aircraft? 

[CoventryWeather]

Should be changed to when will we hit 45, as others have mentioned. 

Relating to July 2022, if the warmest airmass arrived that touch earlier/later, then we would have exceeded 41/42 - if I remember correctly the temperature stopped quite early in the afternoon as cloud approached. Even without this we would have seen a much higher value. Either way quite a significant event, perhaps one that's not likely again in the coming years. 

[WYorksWeather]

 LetItSnow! The July 1808 heatwave I would note, however, is definitely before the introduction of the modern Stevenson screen, which only came in in the 1860s. I actually can't find a reliable source that refers to the 41C any more (Trevor Harley's site which I think is the original source no longer mentions it, and I couldn't find a source elsewhere).

I would also note it as extremely dubious, given that we didn't even reliably record 37C until 1990, despite over a hundred years of Stevenson screen readings before that. I have no doubt though that it was an impressive heatwave. Multiple sources do state a temperature of 100F in the shade in central London, or about 38C. Accounting for urban heat islands you can probably take a degree or two off that for what you would get at a modern official station, which would give a reading of 36-37C. Possible an isolated 38C could have been recorded somewhere in the south or east maybe if it had happened in modern times.

I could perhaps accept that it beat the pre-1990 record for the 20th century, but I can't see how it could possibly have done so by such a large margin (over 3C!), and then that record not even be approached, let alone broken, for a century and a half until some of our modern records. That just stretches credulity to breaking point.

[WYorksWeather]

 CoventryWeather I think the absolute theoretical maximum for the UK on the 19th July 2022 was probably around 42-43C.

I think 45C would require something beyond that, probably on the scale of the Pacific Northwest heatwave in 2021. It's probably just theoretically possible, but at the moment I'd happily put the odds at near zero for e.g. this summer. And when I say near zero, probably 0.1% per year or lower at the moment. But because of the way the chance grows with even a small rise in average temperature, I think it's possible we may get close by 2050, and I expect it to have happened more than once by 2100.

[LetItSnow!]

 WYorksWeather I don't think that it was actually 40C at all but they had asked if there was ever an unofficial recording. There was also an unofficial reading of 42C in July 2006 which is even more ridiculous.

[WYorksWeather]

 LetItSnow! Yeah I'm absolutely sure that there will be multiple such readings in the past. You see it these days as well with people quoting their car thermometers!

The key I think with past readings is to rely more on coarser averages. I trust some of the older CET readings at the monthly level because that is much less prone to bias than one rogue thermometer measurement, prior to the days of modern siting and observation standards.

[Scorcher]

 Derecho It's actually fascinating looking back at this thread and seeing the posts from 2013.

Lots of people were completely wrong and were dismissing the possibility completely.

A few posts even said the Bawtry (South Yorkshire) temperature of 35.6C from 1906 was definitely wrong as it was impossible for it to get that hot so far north- even in mid summer.

The UK all-time record is now in Lincolnshire which is almost as far north as Bawtry. 39C+ was reached quite a lot further north than Bawtry as well.

Imagine their reaction if we could go back to 2013 and tell the people in this thread about the 2022 spell. They would probably fall over laughing.

[MattStoke]

 IanR Funniest thing I've read on here. What nonsense.

[Scorcher]

 MattStoke Pretty comical. Since that post, we've reached 30C pretty routinely in NW England every summer and have gone well past it a few times. Temps of 32C+ have become much more common.

[LetItSnow!]

 WYorksWeather Reminds me of my old weather station I set up when I was 12, not knowing the correct way to install and not being in the shade correctly. I remember recording 39.9C on July 1st, 2015 and thinking "wow!" but obviously it was because the station was being cooked by the sun!

[MattStoke]

 Scorcher Yep. 30'C is almost common most summers now in the South East (Although there weren't a lot of such days last summer but still some).

[raz.org.rain]

 Scorcher it's interesting to see how people reacted to that abnormal run of cooler and wetter summers in the late 2000s and early 2010s. It doesn't surprise me that some latched onto the cooling myth. I think even before that run of poor summers, hitting 30°c in summer wasn't all that unusual, it just so happens that it's practically a given now that CC has grown into a bigger issue. As you say, even in the north you can expect to see 30°c or more in summer, it's nothing noteworthy these days.

[Methuselah]

 raz.org.rain Indeed. And they were also being fed a litany of cack about a so-called LIA footprint. . . 

[kold weather]

There are a couple of things that stand out with the Jul 22 spell beyond just the 40c (Which whilst amazing perhaps is one of the lesser feats). For example it obliterated the daily CET record, nothing is even close (the day before in itself was nearly a record I believe) and thats a 350 year record, so on that metric is comfortably the most severe day in modern history.

The min temperature record was beaten by something like 3c which is very impressive.

The breadth of heat was also outrageous. Normally when a record goes it is the odd 1-2 stations breaking it by maybe 0.5-1c. In this heatwave 46 different stations exceeded the previous record and many more beat their all time records as well.

The best way to view the exceptional nature of it is to compare with other exceptional days:

The day before was probably the hottest day for a fair part of England and Wales but was in the same sort of ballpark as 03 and 19, but for England in particular the 19th July was absolutely another level above anything ever seen before. 

Its perhaps easy to underestimate just how extreme that event was. I've no doubt in a warming world this will happen again, but I think we are still some way off from it being even a uncommon occurrence, at least to the extent it was. 

[WYorksWeather]

 LetItSnow! I also remember a 43C on a car thermometer once when it had been sat in the sun for a very long time. It was a very hot day, but more like 33C than 43C!

[Scorcher]

 kold weather July 18th 2022 was similar to some other exceptionally hot days in previous years in the south- however further north in England and in North Wales it was easily the hottest day on record for many places before it was smashed again the next day.

 

[Arctic Hare]

A little confusing having this thread for 40 °C being revived *and* a separate but heavily overlapping thread about the prospects of 43 °C!

[Scuba steve]

Considering it hasn’t stopped raining for 3days here I would happily settle for 20 c and sunshine