Scores of beachgoers camped overnight to secure good spots in Dorset as thousands of Britons descended on the coast on Sunday.
Baking hot temperatures of 30C and over for many parts of England saw sunseekers battling for space on a number of beaches on the south coast.
Officials in Dorset urged people to avoid Lulworth and Durdle Door due to large numbers already in the coastal areas.
Police were forced to close roads to manage traffic as drivers slept in their cars on Saturday night near Bournemouth beach to secure a seafront space for Sunday.
Thanet District Council said Ramsgate Main Sands beach in Kent was "extremely busy", with high tide likely to make social distancing difficult.
Drivers waited for hours to get into Camber Sands in East Sussex with some beachgoers reporting queues of up to two miles in length.
Blackpool Police also reported its beaches being busy and it had a "larger than usual" number of children going missing.
In Norfolk, police recovered a body from the water at Bawsey Pits near King's Lynn following reports of a man getting into difficulty in the water.
On Saturday, HM Coastguard dealt with 340 incidents across the whole of the UK - the highest number of call-outs in a single day for well over four years.
The Coastguard co-ordinated search and rescue responses to a wide range of incidents, including people being cut off by the tide and children swept out to sea on inflatables.
In total, the service rescued 146 people and assisted a further 371.
The mercury is forecast to reach 35C on Sunday - with Kent, Sussex and parts of London being the most likely to see the highest temperatures, according to Met Office forecaster Craig Snell.
Southern and central England will enjoy temperatures in the high 20Cs on Sunday, while cloud and breezes in some places may result in milder weather in the high teens.
Mr Snell said: "There is some contrast. For some of us the heatwave will continue on Sunday and beyond."
Saturday's top temperature was 34.5C - which was recorded at Frittenden in Kent, Wiggonholt in West Sussex, and Herstmonceux in East Sussex, the Met Office said.
Friday saw the hottest August day in 17 years, with the mercury hitting 36.4C at Heathrow and Kew Gardens.
Yahoo News UK has contacted Dorset Police and Dorset Council for comment.