Parts of the UK could be hotter than Hawaii and Athens today, but forecasters have warned of possible heavy rain and thunder ahead of changeable weather over the bank holiday weekend.
Temperatures could reach 27C (80.6F) in London and East Anglia on Friday, the Met Office said, making it the warmest day of the year so far and hotter than Honolulu, Hawaii's capital, where highs of 26C are forecast.
Friday's highs will be around 10C (50F) higher than the average for this time of year, which is between 15C (59F) and 17C (62.6F), the Met Office said.
Cardiff, meanwhile, could be warmer than Athens, with forecasters predicting temperatures could reach 19C (66.2F) in the Welsh capital.
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However, the warm weather falls short of the record UK high in April, which was 29.4C (84.9F) recorded in central London in 1949.
Met Office meteorologist Simon Partridge told the Press Association: "We've got some very warm, humid air coming up from the south.
"That means we will see some very warm weather, particularly in the east and the South East, because there we'll see the best of the sunshine."
However, Mr Partridge warned that it "doesn't mean everybody's going to get a warm, dry, beautiful day".
The central spine of the UK – in parts of Scotland, the Pennines and the Midlands – could see some heavy rain and thunder.
The Met Office also warned the weather over the bank holiday weekend will be "a different story", with bright spells and showers expected on Saturday and rain forecast for most of the country on Sunday.
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Mr Partridge said: "By the time we get to Monday, we're actually going to see temperatures roughly where they should be for this time of year.
He said temperatures would likely be around 11C (51.8F) to 12C (53.6F) in the north, with the south expected to experience temperatures of up to 16C (60.8F).
"So it will feel quite fresh and chilly compared to what we've had," Mr Partridge added.
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