Boris Johnson failed to appear at a ministers' meeting as he took the weekend off, while deputy PM Dominic Raab said people should "enjoy the sunshine" as temperatures are bound to reach 40 degrees Celsius on Monday.
The UK Prime Minister Boris Johnson and his cabinet were accused on Sunday of not taking the impending heat emergency seriously as forecasters warned of its risk to human lives.
Johnson missed a crisis meeting of ministers in Downing Street on Saturday while taking a weekend break at his country retreat, Checkers. Johnson was also hosting a farewell party for friends on Sunday before he leaves office in September.
Deputy Prime Minister Dominic Raab then spoke of the likelihood of temperatures topping 40 degrees Celsius in England for the first time in a welcoming tone.
"Obviously there is some common-sense practical advice we are talking about -- stay hydrated, stay out of the sun at the hottest times, wear sun cream -- those sorts of things," Raab told Sky News on Sunday.
"We ought to enjoy the sunshine and actually we ought to be resilient enough through some of the pressures it will place," he added, insisting there was no reason for schools to close when the temperatures peak on Monday and Tuesday.
The comments raised eyebrows, as did Johnson's absence from the Downing Street meeting about the government's response to the heatwave. He was forced to resign because of parties held during COVID-19 lockdowns, amongst other reasons.
Speaking after Raab, College of Paramedics Chief Executive Tracy Nicholls said: "This isn't like a lovely hot day where we can put a bit of sunscreen on, go out and enjoy a swim and a meal outside."
"This is serious heat that could actually, ultimately, end in people's deaths because it is so ferocious," she said.
"We're just not set up for that sort of heat in this country."
Met Office issues first-ever extreme heat warning
Contrary to Raab's sang-froid, after Saturday's meeting, government minister Kit Malthouse warned that transport services face "significant disruption" during the heatwave and said the public should work from home if possible.
The UK capital is expected to see the highest temperatures, and mayor Sadiq Khan advised Londoners only to use public transport if "absolutely necessary".
Ambulance services are on crisis alert, and some schools in southern England have already said they will remain closed.
Police urged the public to stay out of waterways after a 16-year-old boy drowned in a canal in the Manchester region, northwest England, on Saturday.
The Met Office, Britain's state meteorological agency, has issued a first-ever "red" warning for extreme heat, cautioning there is a "risk to life" and attributing the heatwave to man-made climate change.
Britain's highest recorded temperature is currently 38.7C set in Cambridge on 25 July 2019, but that looks set to be surpassed in the Met Office's projections for this week.