Britain's heatwave shows no signs of abating, with the mercury set to rise to a scorching 33C (91.4F) later in the week.
Parts of the UK are currently hotter than Athens in Greece, and on a par with Kuala Lumpur in Malaysia and Rio de Janeiro in Brazil.
Temperatures peaked on Monday at 30.1C (86.2F) in Hampton in west London, with all of the UK enjoying a rain-free sunny start to the week.
The Met Office's heat-health watch alert is currently at level two, meaning social and healthcare services are at the ready to reduce harm from a potential heatwave.
Police have urged people to be careful of the temptation to swim in open water in the hot weather.
Surrey Police said: "With the warm weather, we are reminding people of the dangers of swimming in open water."
The warning came after the body of a man was recovered from a lake in Nutfield on Monday.
Firefighters are still at the scene of a large fire on Saddleworth Moor between Stalybridge and Dovestones, which spread overnight.
Greater Manchester Fire Service said the blaze had "devastated a portion of the area near to Buckton Hill".
Footage released by Derbyshire Fire Service showed firefighters, surrounded by smoke, beating down the moorland.
They advised people in the surrounding areas to keep doors and windows closed.
Dr Thomas Waite of Public Health England urged people to keep in mind those who may be vulnerable, including the elderly, young children and those with underlying health conditions for whom he said "the summer heat can bring real health risks".
He added: "That's why we're urging everyone to keep an eye on those you know who may be at risk this summer.
Temperatures are set to rise, with a possible high of 33C (91.4F) on Thursday, meteorologist Alex Burkill said, soaring above the UK average for this time of year of 17.3C (63.1F).