There was some cirrocumulus in the east here in Cambridge before around 6:30am when the sun finally rose above it. Can't see any cloud  to the south now although there is some to the west. The sun is ostensibly in clear skies but it feels somewhat hazy.

Now 28.4c here

Yes it's a significant upgrade (in my book anything cooler is an upgrade!). Three or four degrees lower than forecast last night. As you say, by 5pm the cold front is sweeping east and temperatures do not get above 38c anywhere.

I think some parts could hit the record quite early today - maybe 1/2pm. 

I’m just hoping my lawn receives a drenching later tonight!

For many esp in eastern areas, tonight will probably be more uncomfortable to sleep due to the humidity.

A tropical night here minimum 20c. Slept out in the garden last night,very pleasant!

Some incredible minimums from around the uk and another record gone. Today is the day though,i will be very dissapointed if somewhere does not hit 40c,it has to surely!!

Actually the discussed areas are still likely to peak during 3-5pm.

Fireworks down here.. quite unusual for Cornwall. A very tropical feel.

A non-standard 26C at 0630; but a noticeable SE breeze picking up so maybe not progressing to really high temps here today

Pretty sure official minimum is 09Z-09Z from memory and also the temperature notes on the climate extreme website. Emley Moor was slightly cooler at 09Z yesterday so Kenley has the highest minimum at the moment.

A new UK maximum temperature record is expected. The chance of reaching 40C is considered to be quite high. Update 08:00 BST,19/07 https://t.co/kPQW8NPNYh pic.twitter.com/yVeMZ9q4W1

— TheWeatherOutlook (@TWOweather) July 19, 2022

Here's Cambridge University's computer lab weather station. Non-standard and located on a roof, it seems to under-read at higher temps.

However, useful for a relative comparison, here's a graph I knocked up showing how far ahead today is compared to yesterday and 25-July 2019:

All the data is here: https://www.cl.cam.ac.uk/research/dtg/weather/

All about keeping the illegal clouds away long enough today.  If the East can stay clear until 2pm that's probably enough to break the record. 

Not sure they have the daily minimum correct but the met office have tweeted about the daily mins.

https://twitter.com/metoffice/status/1549289066524545025

Xioni’s comment on the previous page is interesting, and he knows what he’s talking about (reading between the lines I think either an extremely good amateur or a professional meteorologist).

Lifting of the trough: ie the surface feature that is sucking in the hot air from the continent stops doing so. That would make sense, as the revised cooler forecasts don’t show more cloud.

Oh Xioni knows his onions no question.  Let's just hope we can squeeze 40c today somewhere.  Such a huge build up to today.

Expecting 40 today and was 22C last night now 27C as the large tree shadwo from 2 neighbours away are moving away from my garden this will shoot up.  Hope to see 40C by noon.  Skies not clear as we expected on desert dry heat type.  Seeing only blue skies on Namibia Cam this morning really miss seeing proper blue skies this year.

The skies in the gulf every time I’ve been there were very hazy, just like today. Just imagine you’re in Bahrain or Abu Dhabi.

30c already at Biggin hill.  That must be a record for the earliest 30c ever recorded in the UK