A yellow thunderstorms warning for west London has been issued by the Met Office on Friday (July 20).
According to Met Office forecasters, thunder, lightning and rain showers could continue into Saturday (July 28) and bring the lengthy dry spell to an abrupt end.
The warning is in place from 2pm on Friday afternoon until 2am on Saturday and affects Hounslow, Hillingdon, Ealing and Uxbridge.
West Londoners have been warned flash floods and travel chaos could following the thunder.
As much as 30mm of rain could fall in one hour and large hail, lightning and strong winds could pose additional threats.Lightning strikes could cause power cuts in the capital and disrupt traffic and public transport.
A Met Office spokesman said: "There is the potential for thunderstorms to develop during Friday afternoon, lasting well into the evening and perhaps developing into larger areas of heavy rain.
"The thunderstorms will clear away after midnight, perhaps lingering in the far north east of England into the early hours of Saturday. Where the thunderstorms occur torrential downpours are possible with as much as 30mm of rainfall in one hour and 60mm in three hours.
"Large hail, frequent lightning and strong, gusty winds will be additional hazards. However, many places will see much lower rainfall amounts."
Here's what the Met Office says west Londoners should expect from the thunderstorms
- Flooding of homes and businesses could happen quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds
- Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services
- Spray and sudden flooding could lead to difficult driving conditions and some road closures
- Power cuts might occur and other services to some homes and businesses could be lost