Predict the hottest day of 2024 (UK) Competition

[sunny_vale]

I'll go for 39.5C at Heathrow airport on the 27th of July. 

[virtualsphere]

36.1C, Heathrow, July 29th.

[CryoraptorA303]

 virtualsphere I will actually rage if we have another 36.1°C added to the list! Seriously, the only 36s we ever seem to reach are 36.1°C, 36.4°C and 36.7°C, with Wisley getting the one-off 36.5°C in 2006. Why can't we have 36.3°C, 36.6°C, 36.8°C or 36.9°C for a change, if it has to happen at all?

Note, before anyone says Barbourne reached 36.6°C in 1990, go and look at the top temps that day on Starling's Roost, and then come back and tell me it's legitimate The max on that day was actually 35.2°C at Harwarden, another oddly overrepresented decimal in the series.

[raz.org.rain]

I guess I should add some more detail to my prediction... I'm going for 39.3°c on July 14th.

[Greyhound81]

 CryoraptorA303 Do you think there will be another year when 30 degrees is not reached in the UK?  Has been a long time since it last happened, and the chances of it happening will get even lower in future years (unless the AMOC shuts down).

[Met.]

33.2°C, Chippenham Water Works, 17th August.

[raz.org.rain]

 Greyhound81 rather ironically enough, if the AMOC collapses then +30°c summers are effectively guaranteed.

[CryoraptorA303]

 Greyhound81 Maybe if there's a big eruption or we get a mild summer on the order of a 300+ year return period, otherwise it's essentially guaranteed.

We can now probably be expected to not reach 30°C about as often as central France didn't in the 19th century, which is to say almost never.

 Met. Think you mean Cippenham, Chippenham is on the other side of the Cotswolds 

[BlueSkies_do_I_see]

 Greyhound81
The average hottest day Pre 1990 (1875-1989) was 31.9C.
The average hottest day Post 1990 (1990-2023) has been 33.7C.

This is a difference of 1.78C.

The last summer to not reach 30C was 1993.  (29.7C)

For me going forward, we will see only 1 in 10 summers not reaching 32C.

Will we ever see a summer not reach 30C again?  I wouldn't bet on it for sure in my lifetime, but as CryoraptorA303 just said, it would have to a volcanic eruption, or a freak year (maybe 1 in 50?)

Edited March 19 by BlueSkies_do_I_see

[CryoraptorA303]

27 minutes ago, BlueSkies_do_I_see said:

The last summer to not reach 30C was 1993.  (29.7C)

Which funnily enough was in itself a volcanic eruption year, or at least in the aftermath of it, so even then it already required some sort of external event.

[Weatherman_93]

July 19th 43.1C

[CryoraptorA303]

 Weatherman_93

[Metwatch]

Won't enter until closer to the deadline, but a good bet these days is usually going for somewhere in the mid 30s, between 33-37C that's the most likely area. However anything in the 31.5C - 40.5C range is pretty much possible in the next several years.

[PermaCloudFU]

23.675 C, 17 August, Heathrow 

[CryoraptorA303]

 PermaCloudFU Bloody hell, do you have some insider information about a supereruption

[Roger J Smith]

37.2 C at Northolt around July 22nd. 

[summer blizzard]

32.9C on July 5th.

[BlueSkies_do_I_see]

1816 was the last time we had a high summer temp anywhere near 23C.

We recorded a CET July of 13.4C, the coldest in the series.

Crop shortages aplenty that year. Shows how much we rely on the sun.

I would be interested to know what the highest record temperature was that summer.

 

Year Without a Summer - Wikipedia

EN.M.WIKIPEDIA.ORG

 

Edited April 1 by BlueSkies_do_I_see

[CryoraptorA303]

 BlueSkies_do_I_see If you look at the image, you can see that eastern Europe and a small area of Scandinavia were average or even above average that summer. Unless the eruptions can be definitively linked to specific weather patterns, a coincidental cool, likely NWly regime over the summer must've contributed to how severely it was felt in western Europe.

The Sahel also saw above average rainfall that summer, which would support a southerly jet stream. While its known the jet stream moves south if the globe cools, this is over decades and doesn't occur in a single year.

Based on reports from elsewhere in the world, it seems that weather patterns were heavily distorted and there were also isolated unusually warm events. It's quite possible or even probable that 23°C was well-exceeded for a day or two, possibly in an unusual season. If the records were available, 1816 could potentially be the only year with an April or October annual maximum.

Since 1875, the lowest annual maximum was 26.8°C in 1879, so pre-climate change it seems that very low annual maxima were occasionally possible. I've no idea how 23°C could be an annual maximum today barring an extremely severe eruption or series of eruptions. Even 1816 is a fairly hard ask for us not going above 23°C once from April-October.

Edited April 1 by CryoraptorA303

[BlueSkies_do_I_see]

Yes, the UK was badly affected, but not as much as France. The jet stream was probably running to the south of France that summer delivering a succession of low pressure systems. I'm sure that's by some distance their worst summer on record.