The UK experienced its warmest night on record on Monday as the extreme heat saw temperatures remaining in the mid-20s.
It comes as a potential high of 41C is predicted for Tuesday, amid growing travel chaos.
Transport Secretary Grant Shapps has conceded the UK’s transport network cannot cope with the extreme heat and said issues on the rails and roads will continue for decades during such heatwaves.
The Met Office tweeted: “It has provisionally been the warmest night on record in the UK.
“Temperatures didn’t fall below 25C in places, exceeding the previous highest daily minimum record of 23.9C, recorded in Brighton on 3rd August 1990.”
A graphic accompanying the tweet showed the highest overnight minimum temperatures recorded were 24.5C in Aberporth, West Wales, 25.8C in Kenley, in the London Borough of Croydon, and 25.9C at Emley Moor, near Huddersfield, West Yorkshire.
As the heatwave continues, Mr Shapps told people to “apply common sense” and “depending on the nature of your journey and reason for it, you might want to consider rearranging your day around it”.
He told BBC Breakfast: “We’ve seen a considerable amount of travel disruption. We’re probably going to see the hottest day ever in the UK recorded today, and infrastructure, much of it built in Victorian times, just wasn’t built to withstand this type of temperature – and it will be many years before we can replace infrastructure with the kind of infrastructure that could, because the temperatures are so extreme.”
Asked if the transport system can cope with the weather, he said: “The simple answer at the moment is no.
“Where those tracks are 40 degrees in the air, on the ground that could be 50, 60, 70 and more, so you get a severe danger of tracks buckling. What we can’t have is trains running over those and a terrible derailing.
“We’ve got to be very cautious and conscious of that, which is why there’s reduced speeds on large parts of the network.”
Asked how long it will take to upgrade existing rail infrastructure to be more resilient, Mr Shapps told Sky News: “Decades, actually, to replace it all.
“Ditto with tarmac on the roads.
“There’s a long process of replacing it and upgrading it to withstand temperatures, either very hot or sometimes much colder than we’ve been used to, and these are the impacts of global warming.”
On Monday the temperature peaked at 38.1C in Santon Downham, Suffolk, making it the hottest day of the year and the third hottest day on record, after 38.7C in Cambridge in 2019 and 38.5C in Faversham, Kent, in August 2003.
Met Office forecaster Rachel Ayers had warned of a “difficult night of sleeping” before “a pretty unprecedented day” on Tuesday.
She said: “The temperature will be very hot throughout the day, before rising as high as 40C, maybe even 41C in isolated spots across England during the afternoon.”
A possible high of 41C will make the country hotter than Jamaica, the Maldives and Barbados – with rail users warned of delays, cancellations and changes to train services.