Thunderstorms likely to cause flooding and power cuts are set to hit England over the next few days but the other nations will enjoy calmer weather.
The Met Office has issued weather warnings for south-east and central England, which will last until 9pm on Thursday and cover the period between 6am on Friday and 6am on Saturday.
Met Office spokesman Stephen Dixon said parts of East Anglia, the Midlands and the South East could be drenched with up to 2in (50mm) of rain in just two hours on Thursday, and up to 2.8in (70mm) on Friday.
“The storms will most likely be coming in on Thursday afternoon and lasting into the evening,” he said.
“Prolonged and heavy rain is expected to spread northwards on Friday, but we’re uncertain about how far north it will progress.
“Parts of the country could see between 50mm and 70mm of rain.”
Following temperatures as high as 28C (82.4F) in parts of southern England on Wednesday, the mercury plummeted on Thursday, and the cooler weather is set to continue across the UK for the rest of the week.
Forecasters have predicted highs of 22C (71.6F) in London, 20C (68F) in Cardiff and 18C (64.4F) for Aberdeen and Belfast on Thursday, with temperatures due to drop a couple of degrees more on Friday.
Between the storms, sunny spells and showers are expected in all areas.
Stormy weather has already caused disruption at a popular beach in Kent, after a lightning strike triggered a power cut at a pumping station and wastewater was diverted to stop it flooding local properties.
Thanet Council warned people not to enter the area of beach below the high water mark between Margate Main Sands and Joss Bay.
Southern Water apologised for the disruption, saying in a statement: “We’re very sorry to report that, due to a lightning strike at Margate Wastewater Pumping Station overnight yesterday, wastewater was released via the emergency outfall into Palm Bay and Margate Sands.
“The site was damaged and suffered a power outage during the heavy storm, and the heavily diluted incoming flows were diverted through the outfall to prevent wastewater backing up and to protect local properties from internal flooding.
“A team had been placed at site in preparation for the bad weather, so was able to immediately begin work to restore services.”
People in Wales and northern England can expect to see cloudy and breezy weather on Friday, while those in central and southern England have been warned to brace for heavy downpours.
England’s much-anticipated Euro 2020 clash with Scotland at Wembley Stadium on Friday evening could be hit with bands of “heavy thundery showers”, forecasters said.
The Met Office has predicted a 90% chance of rain in the area for kick-off at 8pm.