The UK has recorded its second warmest March day on record and the hottest temperature for the month in 53 years, the Met Office said.
The mercury peaked at 24.5C (76.1F) at Kew Gardens in west London on Tuesday, with St James’s Park in the centre of the capital also hitting highs of 24.3C (75.7F).
The figure is only slightly below the UK’s hottest ever March temperature of 25.6C (78F), recorded in 1968 at Mepal in Cambridgeshire.
However, Met Office forecaster Alex Burkill said it was a “possibility” that the record could be broken on Wednesday with temperatures expected to reach around 25C (77F).
He said: “It (the temperature) is exceptionally high for the time of year.
“It’s the second warmest March day on record.
“Temperatures could be a touch higher tomorrow than they were today.
“Whether it will beat the 25.6C, I’m not so sure.
“It’s on a knife edge.
“It’s not out of the question, but I’m not expecting it to.
“It’s a possibility.”
But Matt Hancock said that while people enjoy the sun, they need to be careful not to “blow it” at this stage of the coronavirus pandemic.
The Health Secretary tweeted: “Let’s enjoy the sun but let’s do it safely. We have come so far, don’t blow it now.”
Temperatures increased by more than 20C in less than four hours in Santon Downham, west Suffolk, earlier in the day.
The village saw the mercury climb from a frosty minus 1.6C (29.1F) at 7am to 19C (66.2F) shortly before 11am.
Temperatures are forecast to hit 24C (75.2F) to 25C (77F) on Wednesday, with the highest figures expected around London.
The Met Office earlier tweeted there would be “exceptional warmth” and “massive” temperature contrasts as the month comes to a close.
Mr Burkill said: “The warmth is going to be very widespread across the bulk of England and Wales.
“Northern Ireland and many parts of Scotland will be cooler by tomorrow, so a little bit fresher.
“For most, it will be largely sunny, with a few bits of fair-weather cloud in England and Wales.
“In Northern Ireland and Scotland it will be cloudier with a band of rain edging its way southwards.”
Mr Burkill said Wales recorded its hottest day of the year so far, with the mercury hitting 21.3C (70F) in Cardiff.
Northern Ireland also experienced its warmest day of the year with temperatures reaching 18C (64.4F) at Giant’s Causeway, while Scotland saw the mercury rise to 18.5C (65.3F) in Lossiemouth, Moray.