For thunderstorms and significant rainfall over the weekend, a yellow weather advisory has been issued.
Parts of Essex, Cambridgeshire, Northamptonshire, Buckinghamshire, Hertfordshire, and Bedfordshire are included in the Met Office's warning, which goes into effect on Saturday at 14:00 BST.
Storms are moving in "as a result of a southeasterly change in wind direction drawing up air from the Continent," according to forecaster Dan Holley.
A yellow thunderstorm warning indicates a slight possibility of quick flooding and possible building damage in homes and places of business.
In some areas, Saturday afternoon thunderstorms and a lot of rain are expected.
"A much warmer and more humid air mass will cover the region this weekend, with temperatures possibly getting close to 30C (86F)," Mr. Holley continued.
"This increases the possibility of a few isolated, heavy showers or thunderstorms on Saturday and Sunday, especially in the late afternoon and evening.
The majority of the risky areas will be located generally west of the M11-A10 corridor, while areas further east are likely to remain dry.
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