The UK is set for one of the hottest days of the year, with forecasters predicting temperatures could reach a sizzling 36C in south-east England.
By 13:00 BST, the mercury had reached more than 33C at London’s Heathrow Airport.
Crowds have headed to the coast to enjoy the hot weather, but people have been urged to avoid busy beaches.
Warm weather will continue over the weekend for much of the UK, according to the Met Office.
The highest temperatures are expected in England and Wales on Friday, with fresher weather forecast for Scotland and Northern Ireland, the Met Office tweeted.
As of 13:00 BST, temperatures had reached highs of 33.5C in England (Heathrow), 26.4C in Wales (Usk), 23.5C in Scotland (Charterhall, Scottish Borders), and 20.9C in Northern Ireland (Katesbridge), BBC Weather said.
A high of 36C is expected by mid to late afternoon in the south-east of England.
The sweltering temperatures come just one week after the UK recorded a yearly high of 37.8C at Heathrow.
Councils responsible for beaches are asking visitors to socially distance during the hot weather, and stay clear of packed beaches.
In Dorset, beach-goers have been told to “head home” as resorts and car parks in some areas are already full.
And Thanet District Council in Kent – which warned last month that busy beaches were becoming unmanageable – has asked visitors to look for less crowded areas so they can socially distance.
Meanwhile, the RNLI has called on beachgoers in the south west of England to follow water safety advice and adhere to social distancing.
Last week, the charity carried out 30 rescues in one day on just one beach in Cornwall.
The incidents mainly involved bathers and body boarders caught in rip currents, going out of their depth and being cut off by the incoming tide.
Kitty Norman, water safety delivery support at the RNLI, said beaches across the whole of the South West were “extremely busy” with locals holidaying at home this year as well as an influx of visitors.
She said: “The sheer volume of people making social distancing tricky is one thing to be conscious of before planning your trip to the beach.
“You might choose to visit the beach at a quieter time of day, or choose a beach with more space, where you can still bathe between the flagged area but spread out further when setting up camp for the day.
“If you arrive at the beach and it is simply too crowded, consider moving on and spending your day elsewhere.”
She also asked people to respect a two-metre distance when approaching lifeguards.