Thunderstorms and torrential rain are set to sweep across the UK, bringing an end to a week of blazing sunshine and scorching temperatures.
The Met Office has warned Friday’s storms could bring lightning, hail and flooding to some areas, with up to 50mm of rain falling in an hour.
A yellow weather warning is in place for most of England, Scotland and east Wales from midday to 9am on Saturday.
Met Office meteorologist Craig Snell said: “Not everyone will see a storm, but if you catch one, you will certainly know about it.”
The south-west and part of the south-east coast of England is not covered by the warning.
It comes after the UK experienced its hottest day of the year so far on Thursday, with the mercury rising to 33.4C (92.1F) at Heathrow Airport in west London.
Large crowds seen on England’s beaches prompted Health Secretary Matt Hancock to threaten to close them if the public does not social distance.
The latter saw temperatures rise to 31.4C (88.5F) in Trawsgoed, near Aberystwyth.
Temperatures on Friday are forecast to reach 31C (87.8F) in London, the mid-20s for the rest of England and up to 27C (80.6F) in the Scottish Highlands.
The storms are expected to clear northeastwards on Friday afternoon and into the evening, but will remain over north-east Scotland until Saturday morning, the Met Office said.
The Environment Agency issued two flood alerts – meaning flooding is possible – for the waterways around Loughborough in Leicestershire and the River Trent tributaries in Nottinghamshire.
Temperatures are expected to drop on Saturday to 22C to 23C (73.4F) in London, and stay around the “high teens to low 20s” for the rest of the UK, Mr Snell said.
He added: “It (the weather) will change, but it will be more what people expect our summer to be like – a mix of sun and showers.”
Earlier on Thursday, Bournemouth, Christchurch and Poole council said it was left with no choice but to declare a major incident after services were “completely overstretched” as huge numbers of visitors defied advice to stay away from its beaches.
Condemning the “irresponsible” behaviour of crowds who gridlocked roads, dumped rubbish, abused refuse collectors and parked illegally, the council said extra police patrols have been brought in.