A plume of roasting air from Africa will bring the highest temperatures for a year and threatens to topple the all-time summer record.
Forecasters predict a rapid warm up over the next five days with temperatures expected to hit a sizzling peak just after the weekend.
Much of the UK faces a repeat of last month’s heatwave which saw the mercury push past the 33C (91F) mark in parts of the country.
However this time round thermometers look poised to soar even higher with the 2003 record for the warmest ever temperature of 38.5C (101.3F) now under threat.
The impending heatwave has sparked a raft of warnings to those heading out and about this weekend to take extra care on the roads.
Motoring experts are urging people to pack bottled water and make sure cars are prepared for the extreme heat.
Roads start to soften at around 27C leading to cracks and ruts on tar surfaces while the temperature inside stationary cars can hit 60C (140F).
RAC traffic watch spokesman Rod Dennis said: “After a cooler spell of weather, drivers are soon going to really start to feel the heat.
“During the last mini heatwave, we saw breakdowns caused by problems with cooling systems jump by nearly a quarter.
“Drivers need to make sure they keep their cool – we’ve previously seen a rise in temperatures lead to a spike in accidents, perhaps caused by increased driver fatigue and frustration on congested roads.”
The Met Office said things will start to warm up dramatically from Thursday as a swathe of hot air sweeps in from the Continent.
By the weekend southern parts of Britain will be sweltering in temperatures in the high 20Cs with 32C (90F) likely by Tuesday.
Although the north will be slightly cooler the mercury could nudge 28C (82F) even in the far reaches of Scotland.
James Madden, forecaster for Exacta Weather, said this weekend could mark the start of a two-week heatwave with warm weather expected to hold out through much of August.
“The good news is that it also looks like hanging around for quite some time, and we could see at least a 1-2 week spell of excellent summer-like conditions for most and if not all parts of the country within this period.”
Netweather predicts 100 per cent humidity over much of the country next week will make it feel close to 35C (95F) in parts of Britain.
Bookies have in the last few days started slashing the odds on Britain hitting the 100F mark by the middle of next week.