A high of 25C (77F) was recorded yesterday afternoon in Gravesend, Kent, and St James’s Park in London – with the summer-like temperatures putting the likes of Athens and Rome in the shade.
Thursday’s temperatures are expected to better this, too, with 26C (78.8F) expected in some parts of the country.
The Met Office says 28C is “possible” in London.
By comparison, the average maximum temperature for April is a mere 11.4C (52.5F).
Warm air off the coast of Portugal has been dragged up towards the UK by an area of low pressure over the Atlantic and high pressure over western Europe, according to the Met Office.
Its spokesman Oli Claydon added: “After quite a dull and chilly start to spring this is the first bout of real warm sunshine that we’ve seen.
“The sun at this time of year is nearly equally as strong as it can be in the summer so people just need to be cautious of that and make sure that they do look after themselves.”
The bout of hot weather could prove problematic for runners during this weekend’s London Marathon, as temperatures on Sunday have the potential to beat the current record of 22.7C (72.9F), which was set in 1996.
But it might not be all bad news for competitors who are hoping for cooler conditions, as there is a chance cloud cover could lower temperatures.
Yesterday, sun worshippers took the chance to soak up some rays, with Brighton beach full of people enjoying the heat.
Average temperatures stood at 24C (75.2F) across the South East – the same as sunny Madrid and two degrees higher than Rome and Athens.
Unfortunately, the glorious weather is not expected to last.
Temperatures are set to fall across the UK from the beginning of next week, with some showery outbreaks predicted.
The Met Office’s forecast for Sunday into Monday is: “Thundery showers in the north and west becoming more widespread. Unsettled, cooler and breezy on Monday.”