Friday has been the hottest day of the year so far, the Met Office confirmed, with a temperature of 31.2C recorded at Heathrow Airport.
The previous record high for 2024 was 30.5C in Wisley, Surrey, on June 26.
The Met Office said the temperature on Friday could increase further, and it is likely to remain very warm overnight.
Highs of 32C were predicted in St James’s Park earlier by the forecaster.
A yellow heat alert from the UK Health Security Agency is in place in the East Midlands, East England, London and the South-East until Saturday. It warned that expected hot weather may have minor impacts on the health and social care sector.
The Met Office also warned hay fever sufferers that pollen levels would be high today in almost all areas of the UK.
But things will begin to cool down over the weekend and there could be thunderstorms overnight into Saturday.
Saturday’s highest temperature will be 28 or 29C, with the warmest spells likely to be seen in the east and south-east of England.
On Sunday the weather will have a cooler, fresher feel to it, but it will still be warm and mostly dry.
Saturday will be another very warm day in eastern England but feeling cooler for the rest of us 🌡️
— Met Office (@metoffice) July 19, 2024
More typical late July temperatures for all of us by Sunday with temperatures some 5 or more Celsius lower in places 📉 pic.twitter.com/sPt7ebf9Ox
The Met Office said: “We could see some very heavy bursts of rain as the day (Saturday) progresses, with the potential for thunderstorms in eastern England on Saturday afternoon into evening.
“Some heavy rainfall in narrow corridors across the north-western half of the UK is also likely on Saturday night into early Sunday.”
The hot weather is a welcome change for the UK after a wet start to July. In the first week of the month, several areas in the South-East including London saw 80 per cent or more of the average expected rainfall for the whole month, according to Met Office data.
Meanwhile a heatwave continued to grip southern Europe, with emergency services battling wildfires in Greece and 14 cities in Italy under the highest level of heat alert as temperatures were predicted to climb bove 40C.
