Sun worshippers are set to sizzle in the spring heatwave, with Bank Holiday Monday forecast to be the hottest since records began.
The mercury could hit 28C as people round off their three-day weekend - making it the hottest in 40 years.
The May Bank Holiday was introduced in 1978 and the temperature has never topped the 28C mark since then.
Bank Holiday Monday in 1999 was 23.6C, while the hottest bank holiday weekend ever was in 1995 when temperatures peaked on the Saturday at 28.6C.
Met Office forecaster Craig Snell said the South East, East Anglia and the East Midlands will feel the heat most.
Saturday will see highs of 23C or 24C, and Sunday will see the mercury rise to 25C, with it climbing to a potential 28C in some places on Monday.
Scotland and Northern Ireland will be a little cooler, but even eastern parts of Scotland will reach the low twenties at times.
Mr Snell said: "It looks likely we'll at least see our warmest Bank Holiday Monday on record on Monday.
"23.6C is what we've got to beat, and we're forecasting highs of at least 26C, 27C, possibly 28C, so I think we can safely say that's going to be beaten.
"But whether or not we will beat the record for the whole weekend put together, we'll be close, but at the moment looking at it we may just come short."
The average daytime high for the month of May is around 17C.
The record highest temperature for May is 32.8C which was recorded in 1922 and 1944.
Bookmaker Coral has cut the odds on this month seeing the hottest May day ever recorded to 6-4 from 2-1.