Buses and cars have been left stranded after thunderstorms flooded roads across London.
The Met Office has issued an amber warning for storms covering London and parts of the home counties where homes and businesses are at risk of flooding, lasting until 7pm on Sunday.
A yellow warning for storms that could cause travel and power disruption also covers a wider area of the south from Norwich to Plymouth, and lasts until midnight.
Social media users posted videos of partially submerged vehicles in south-west London, with more heavy rain expected to fall as a band of thunderstorms made its way across south-east England.
The Met Office meteorologist Steven Keates said parts of southern Suffolk and the Isle of Wight could receive 100mm of rain in a few hours on Sunday evening.
“There’s torrential thunderstorms around yet again,” he said. “Into the evening, from Norfolk to Bournemouth we are going to see some pretty lively showers.
“Torrential downpours, thunder and lightning, and potentially some hailstones are settling in the south.”
Keates said the storms were being caused by a convergence of air currents as warmth in the Earth’s surface from the recent heatwave rose to meet cooler air in the atmosphere.
Kingston police, who oversee a borough in the amber zone for storms, told motorists to drive carefully and remember they are “not driving a submarine”.
Police closed a road near Queenstown Road station in south-west London, where three doubledecker buses were stuck under a railway bridge, according to a journalist from Agence France-Presse . A driver said passengers had to get off after his bus started taking on water.
Other motorists in Walthamstow, north-east London, abandoned their vehicles as torrential rain fell.
Police said they were “currently dealing with numerous floods in the east,” and that tunnels and roundabouts were submerged.
The rest of the country was forecast to experience a cloudy, more settled end to the week while sunshine was expected in Scotland.
Temperatures are expected to rise in most places again on Monday as the storms clear, with 26C forecast for London, 25C for Edinburgh, 24C for Cardiff and 22C for Belfast.
The Met Office has predicted early cloud in some northern and eastern parts which will move up to Scotland, and sunny spells and scattered showers in most places throughout the day.