The scorching UK heatwave is set to trigger thunderstorms across London and the south-east today with an official warning in force from forecasters.

A yellow warning for thunderstorms is in place from 2pm until midnight and extends across the capital, the south of England and east midlands. 

The Met Office has warned that the heaviest showers could see 30mm of rain in an hour brining the possibility of flooding in some areas.

Forecasters said the increasing heat and humidity was behind the storms. 

Londoners caught in rain on Oxford Street during thunderstorms (PA Wire/PA Images)

Areas under the yellow alert have been warned that the  weather could affect transport with some cancellations to train, bus and Tube services. 

While spray could lead to difficult driving conditions.

Steven Keats, forecaster at the Met Office, told the Standard: "It will be a bright morning with sunshine.

"This afternoon there is a risk of showers with scope for local downpours and flooding leading to bad conditions on the roads. Temperatures should still top 27/28C."

The hot weather will continue throughout the weekend with the mercury topping 29C on Saturday however there will still be a risk of thunder.