Emergency services have responded 45 flooding incidents across London as heavy rain from Storm Claudio hit during the morning rush-hour.
London Fire Brigade received a number of calls from people trapped in their cars, as well as property flooding.
The Brigade is warning people to avoid driving or walking through floodwaters and not to let children or pets play in it.
A video posted to Twitter shows a number of cars driving through flood waters - including a Thames Water van - during the morning rush-hour in West Drayton, in Hillingdon.
Flood warnings have been issued by the Met Office and Environment Agency across England, including in west London near Ruislip, Wembley and Harrow, and in north London near Waltham and Cheshunt.
A yellow rain warning has been issued for southeast England, with the Met Office warning that flooding on roads will make journey times longer. Up to 30mm of rain is expected.
The downpours have been described as “biblical” by some commuters. One driver on Twitter said they are “probably the wettest and worst conditions I’ve ever driven in”.
A motorist became stuck inside his car as he drove through floodwaters on the A41 at Hendon Way, having to scramble out of the driver’s seat and on to the top of his car, before abandoning his vehicle.
UK Weather: London Flash Flooding | 3rd November 2022
Sections of the M25, the A41 and and A1 in north London are blocked.
A number of Underground lines are part suspended or severely delayed. There were reports of major flooding near Finchley Road Underground station.
Some train services have also been cancelled or delayed.
“Due to heavy rain flooding the railway between Fulwell and Hampton, all lines are blocked,” Southwestern Rail said in an update.
Thameslink said no trains can call at Mill Hill Broadway station due to flooding. Tickets are vaild on London buses.
Heavy rain is forecast most of Thursday morning, but will clear in the afternoon with a risk of isolated heavy thundery showers following later, the Met Office said.
The heavy rain is a result of Storm Claudio, which passed over northern France earlier this week.