Brits will sizzle on the hottest August Bank Holiday weekend on record, according to the Met Office.
The thermometer could hit 33C (91.4F) which would smash the previous high set two years ago – by five degrees.
It will mean millions will take to the road for day trips to the seaside and other outdoor attractions.
Tourism chifs say a record 8.6 million Brits plan holiday at home this August Bank Holiday, bringing £2.1 billion boost to economy.
High pressure sweeping in from the Atlantic is bringing an end to the unsettled weather of the past couple of weeks.
Chief Met Office meteorologist Steve Willington said: “By Bank Holiday Monday itself temperatures will rise further with around 33 Celsius possible in the southeast – which would set a new record for the coming Bank Holiday weekend.”
The current highest temperature on record for the UK is 28.2˚C at Holbeach, Lincolnshire in 2017.
Mr Willington said: “We’ve had a fairly wet and windy August so far.
“However that’s going to change this weekend as we see high temperatures, sunshine and light winds return.
“On Saturday and Sunday there’ll be plenty of sunshine across the country with temperatures reaching into the mid-20s Celsius for many.
“It’ll be warmest in southeastern parts where 30 Celsius is possible.
From Friday south easterly winds will draw warm air from Europe towards the UK, bringing rising temperatures along with dry and settled weather.
Monday is also set to be the hottest day ever recorded across the whole weekend break. In 2001 the thermometer reached 31.5˚C at Heathrow.
The return of the heat will be a huge welcome after days of washouts that sparked flooding chaos.
RAC spokesman Rod Dennis said: “With summer returning in time for the weekend for many of us, it’s going to mean millions of us take to the road for day trips and short breaks.
“Unfortunately, as the temperature rises so can the chances of a breakdown – so it’s important drivers check over their vehicle before setting out.
“Tyre pressure and tread, as well as oil and coolant levels, should all be looked at and doing so can really cut the chances of breaking down.
“Hungry, thirsty or tired passengers can also be recipes for in-car irritability – and ‘carguments’ – so pack enough food and water to keep your passengers happy, and plan in enough breaks along the way.”
With temperatures expected to be well above average for the time of year, heatwave thresholds will be met across many parts of the country.
The Met Office has issued several heat health alerts in partnership with Public Health England.
On top of the incoming heatwave, Britain could also be in for a long warm spell with summer weather set to hold out into the start of autumn, according to some long-range experts.