A THUNDERSTORM warning has been issued by the @MetOffice for Essex until 6AM Monday. From late afternoon through Sunday night, there is a small chance of thunderstorms becoming severe, with large hail, frequent lightning, gusty winds, and torrential rain producing 30 to 40 mm in an hour.

Further details below.

https://www.metoffice.gov.uk/weather/warnings-and-advice/uk-warnings#?date=2023-09-17