U.K has recorded temperatures of over 40C (104F) for the first time.
Thermometers hit 40.3C at Coningsby in Lincolnshire, while 33 other locations went past the UK’s previous highest temperature of 38.7C, set in 2019.
Several fire services declared major incidents after a surge in fires. A major blaze in Wennington, in east London, left homes gutted.
Some rail services were cancelled after tracks overheated or buckled and overhead cables failed.
Hundreds of firefighters tackled fires across London, including in Wennington, where a grass fire spread to properties.
There have also been fires elsewhere in the country with major incidents declared in Leicestershire, East, North and South Yorkshire and Lincolnshire, Hertfordshire, Suffolk and Norfolk.
Home Secretary Priti Patel said she had been updated on the “dangerous fires” and urged the public to follow safety advice from their local fire service.
In the capital, people were urged not to have barbecues or bonfires and to be careful when disposing of cigarettes.
Two people were taken to hospital to be treated for smoke inhalation after a fire in Dagenham, east London, while further north a nursery was caught in a blaze in Milton Keynes.
London Fire Brigade assistant commissioner Jonathan Smith said some of the fires in the city were the result of “tinderbox” conditions and said yesterday would be “critical” in ensuring the fires were kept under control.