A yellow weather warning has been issued for London as an "Iberian plume" pushes temperatures up to 31C, with the sticky air forecast to trigger thunderstorms.
The UK Health Security Agency (UKHSA)-issued alert came into force at 9am on Friday and will remain in place until Monday 12 June.
Parts of the country are predicted to be hotter than Marbella, Ibiza and Tenerife in the coming days as a “plume of warm air” moves in from the south, with temperatures forecast to soar on Saturday in the capital.
Yellow alerts are used to warn that there may be some disruption to services due to weather conditions.
The Met Office warned showers could be “torrential and thundery”, with more than 30-40mm potentially falling within an hour.
Oliver Clayden, from the Met Office, said there could be some travel disruption over the weekend.
He said: “After a prolonged dry spell there is a chance of surface water flooding.“There could be some surface water issues that could cause travel disruptions as well as the high gusts across parts of the country.”
Mr Clayden added: “This is going to be the warmest weekend of the year, which is to be expected as we go into summer.
"This weekend will also see hail mixed in with strong gusts of wind and rain hit parts of the country.”
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