The UK saw its hottest day of the year so far on Monday as temperatures soared to 38.1C - though the mercury failed to rise above the record of 38.7C.
Forecasters said that the record was likely to be broken on Tuesday, with highs of 41C expected in England.
Wales, meanwhile, recorded its highest ever temperature as the mercury hit a sizzling 37.1C in Hawarden, Flintshire. In Scotland, highs of 31.3C were reported in Aboyne.
Temperatures reached 38.1C at Santon Downham, Norfolk at 4pm today - the third hottest day ever - but not quite eclipsing the 38.7C recorded in Cambridge in July 2019.
At 3pm, Kew Gardens recorded a high of 37.5C.
Met Office meteorologist Luke Miall warned that Tuesday would see even higher temperatures across the country, with the mercury likely to surpass 40C in London and 41C in the south of England.
He said: “I’ve been a qualified meteorologist for 10 years, and telling people about 41C in the UK doesn’t seem real.
“It’s crazy how we are talking about these sorts of values, I’ve never seen the models coming up with these values.”
The Met Office is also warning that temperatures overnight into Tuesday are holding up in the low 20s and possible mid-20s in isolated places, and it looks likely to be the warmest night on record in the UK.
Meanwhile, a third emergency Cobra meeting about the heatwave took place on Monday, though the Prime Minister did not attend.
Downing Street said the NHS is “coping well” with the extreme heat, and no deaths have been reported centrally at this stage.
Commuters in London were urged not to travel during the sweltering temperatures, while health secretary Steve Barclay said the NHS had seen an uptick in 999 calls.
