Flash flooding has hit parts of the South East as thunderstorms washed away the recent heatwave, dumping almost half a month's rain in a few hours.
There were reports of roads and properties being inundated across Surrey, Hampshire, Hertfordshire and Greater London as a band of torrential rain moved in from the Channel overnight, prompting the Environment Agency to issue a series of flood warnings.
The weather front is due to send temperatures tumbling ahead of the weekend, just days after parts of the country baked in 34C (93F) heat.
A yellow warning of rain is in place for much of England during Friday, rising to amber along a narrow corridor west of London where "exceptionally heavy, thundery rain" accompanied by hail is expected.
Surrey Fire and Rescue Service said it had been called to reports of a house struck by lightning near Woking, while crews worked to pump water out of flooded premises across the county.
Transport for London said two Tube stations in west London were closed due to flooding, while there were reports of disruption on the M4.
Fire chiefs advised motorists to avoid driving through flooded roads and turn around as pictures emerged of Maidenhead High Street resembling a swimming pool.
Met Office meteorologist Martin Combe said 32.8mm of rain had fallen in just three hours in Farnborough, Hampshire - nearly half the 70mm average for September.
He said: "The storms are quite slow moving so it means the amounts are starting to build up over time, so we may get higher figures and localised flooding.
"The showers and thunderstorms are going to carry on for quite some time moving slowly north and eastwards, remaining around London through the morning and all afternoon in East Anglia.
"They will eventually clear off to the east, but it will be cool behind them. While it won't be any colder than average it is going to feel a lot cooler than it has been."
Away from the storms Friday will be a relatively cool and fresh day for most of the country with some sunshine.
London is expected to see a high of 21C (70F), Cardiff 18C (64F) and Manchester, Glasgow and Belfast 17C (63F).
Saturday and Sunday are expected to be similarly fresh, although a weather front will bring rain for Northern Ireland, Scotland and Wales on Sunday.