Thunderstorm warnings for most of the UK have been issued, with lightning and hail possible during the summer bank holiday weekend.
The yellow alerts have been put in place by the Met Office for most of Sunday as up to 40mm of rain is possible over several hours in some areas.
Forecasters warned that heavy showers and thunderstorms may impact driving conditions and cause delays to public transport, with the potential for some flooding to homes and businesses.
One warning, which covers south-west England, Wales, parts of south-east England and stretches up to the Scottish border, is active until the end of Sunday.
Another covers parts of Northern Ireland, north-east England and central Scotland, and is in place until 11pm.
Wind gusts of up to 45mph will also be hazardous in some areas, the Met Office said, as it advised those in the warning zones to prepare for potential short-term power cuts.
Met Office meteorologist Kathryn Chalk said people will “need that umbrella at hand” as showers sweep the country that afternoon.
She said: “Through the rest of the afternoon, there are Met Office yellow thunderstorm warnings in force across much of the UK, so expect some heavy, intense downpours, frequent lightning, rumbles of thunder and also some hail mixed in.
“The showers mostly focus across the west through the afternoon and becoming a bit banded, so some longer spells of rain, especially across southern Scotland and northern parts of England.
“Towards the far south and east, that’s where we largely hold on to drier conditions and some sunny spells, but the odd shower can’t be ruled out.
“Some strong winds as well developing, especially across the south-west, and feeling cool underneath any of these intense downpours.”
Highs of 23C are expected in Norwich on Sunday, along with 22C in London and Hull, 21C in Cardiff and 18C in Glasgow, according to the Met Office.
Monday – which is a bank holiday in England, Wales and Northern Ireland – will see a “fine and largely dry afternoon” with showers in some areas, Ms Chalk said.
It comes after music fans at Reading Festival donned ponchos and umbrellas, and frolicked in the mud after getting caught in downpours over Friday and Saturday.
While some were seen flinging mud at each other and playing in puddles, others hid beneath their plastic ponchos as they braved the poor weather conditions.
Elsewhere, the cricket at Lord’s in London was halted by the rain on Saturday.
Festivalgoers heading to Reading and Leeds, Creamfields and other live music events had previously been warned of unseasonably strong winds.
As of Sunday afternoon, seven areas are covered by Environment Agency flood alerts, meaning floods are possible.
