There are growing fears that lives could be at risk as the Met Office said a new UK record temperature is likely to be set early next week.
Meteorologists say there is an 80% chance the mercury will top the UK record high of 38.7C (101.7F) set in Cambridge in 2019.
The heat will peak on Tuesday and temperatures will rise over the weekend.
The Met Office has issued an amber warning to cover most of England and Wales from Sunday to Tuesday.
Daytime temperatures on Saturday are forecast to be around 27C (80.6F) in London, 26C (78.8F) in Cardiff, 23C (73.4F) in Belfast and 21C (69.8F) in Edinburgh. On Sunday it could reach 30C (86F) in the capital, 27C (80.6F) in Cardiff, 24C (75.2F) in Belfast and 23C (73.4F) in Edinburgh.
Temperatures will rise across the country on Tuesday, reaching the mid-thirties across much of England and Wales.
There is a 50% chance of temperatures reaching 40C (104F) somewhere in the UK, with the Met Office issuing its first red warning for extreme heat.
The UK Health Safety Agency has raised its heat health warning from level three to level four.national emergency“.
The fourth level is reached “when the heat wave is so strong and/or long-lasting that its consequences extend beyond the health and social care systems…risk groups,” the statement said.
The Met Office’s red warning for Monday and Tuesday covers an area from London to Manchester and up to the York Valley.
“If people have vulnerable relatives or neighbors, now is the time to make sure they are taking the appropriate measures to cope with the heat, because if the forecast is as we think it will be. in the red warning zone, then people’s lives are in danger.
“This is a very serious situation.”
Train operators are warning passengers to avoid all but “essential” travel
A No 10 spokesman said rail speed restrictions may be necessary “on parts of the network next week to manage the hot weather and avoid potential damage”.
Jake Kelly, from Network Rail, warned that journeys would “take significantly longer and delays are likely as speed restrictions are put in place to keep passengers and rail staff safe”.
Train operators warned passengers to avoid “absolutely necessary” journeys on Monday and Tuesday.
Some schools in the south are also closed on those days.
Motorists have been advised to avoid the hottest parts of the day, especially if they have older cars.
UK heatwave could put lives at risk, Met Office warns, as ‘national emergency’ declared | UK news
Source UK heatwave could put lives at risk, Met Office warns, as ‘national emergency’ declared | UK news