You might expect sunshine in Australia, Tunisia or Argentina, but those staying in the UK are likely to see hotter weather, with some parts of the country expected to reach the high 20s before the bank holiday weekend.

Temperatures in London and East Anglia could reach 27C on Friday, the Met Office said, marking the warmest day of the year so far. The scorching heat means parts of the UK could be warmer than Sydney, Buenos Aires or Tunis, where highs of between 24C to 22C are forecast. Temperatures could also exceed those in Honolulu, the capital of Hawaii, where highs of 26C are predicted.

Friday’s highs in London and the south-east will be about 10C higher than averages for the time of year, which are 15 to 17C, the Met Office said.

“We’ve got some very warm, humid air coming up from the south,” the Met Office meteorologist Simon Partridge told the Press Association. “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.”

Cloud over the central spine of the UK, from Scotland, the Pennines and into the Midlands, could produce some heavy rain on Friday. “Unfortunately, it doesn’t mean everybody’s going to get a warm, dry, beautiful day,” said Partridge.

The clear skies might not continue throughout the bank holiday weekend, with changeable conditions forecast across the UK. “The weekend is a bit of a different story, really,” said Partridge. “There will be some bright spells in there as well on Saturday, but there will also be showers, particularly across northern and western parts of the UK.”

Rain is forecast across the country on Sunday and temperatures will continue to cool towards averages for May.

“By the time we get to Monday, we’re actually going to see temperatures roughly where they should be for this time of year,” Partridge said. “We’re looking at 11s and 12s [degrees celsius] in the north and 15s and 16s in the south, so it will feel quite fresh and chilly compared to what we’ve had.”

The brief hot spell comes after an April that was drier and warmer than average for much of the UK, according to provisional figures from the Met Office. All four nations recorded a higher mean temperature in April than the long-term average.