The temperatures have been experienced around the country with Scotland, Wales and Northern Ireland all experiencing their highest temperatures of the year.
Emma Boorman, a Met Office forecaster said: “It’s the warmest day of the year with St James’ Park in London recording 27.1C
“There’s lots of lovely sunshine out there to enjoy. The final temperatures are still coming in but all four countries in the United Kingdom have recorded their highest temperatures of the year.”
In Scotland, the highest was in Kirkcudbrightshire which recorded 22.5C (72.5F), with Aberporth in Wales reaching 24.3C (75.7F) and Killowen in County Down, Northern Ireland, recording 18C (64F).
Bookmaker Coral is offering even money that 2016 is the hottest year on record in the UK after the firm saw a sustained gamble over the last 48 hours leading them to slash the odds from 3-1.
It is also offering just 2-1 that the record high of 32.8C (91F) is broken in May, while it is 6-4 for 30C (86F) to be recorded this month
Spokesman John Hill said: “Punters are convinced we are set for the hottest year on record in the UK as we’ve seen a sustained gamble in the betting over the last few days.
“We may not have to wait long for 30C or higher to be recorded in 2016 as the odds suggest it is likely to arrive this month.”
Ladbrokes also said bets had been pouring in and it has been offering 2/1 for the mercury to reach 30C or higher before the weekend is out.
Jessica Bridge of Ladbrokes said: “It’s getting hotter by the day and punters are convinced the sunshine’s here to stay all summer.”
Pollution levels are expected to peak on Sunday, with high levels possible locally and widespread moderate air pollution.
Those heading outdoors to enjoy the fine weather are also warned to be aware that UV levels will be high.
From Monday temperatures in Wales may be around 17-23C (62-73F), around 18-19C (64-66F) in Northern Ireland and easterly breezes in areas like Aberdeen will bring 15-16C(59-61F) temperatures to parts of Scotland.
As the week progresses, temperatures are still likely to be mild, but will fall day on day.