The Met Office has extended its yellow weather warning for heavy rain until 7am on Sunday 13 July 2014.
It covers Essex, Norfolk, Southend-on-Sea, Suffolk and Cambridgeshire.
The warning says: "Heavy showers and thunderstorms will continue to move east across East Anglia during the next couple of hours, with a risk of further isolated thunderstorms developing overnight.
"The public should be aware that localised downpours could lead to temporary surface water flooding."
The Met Office Chief Forecaster's assessment: "A line of thunderstorms is currently bringing locally very heavy rain with 15-25 mm of rain falling within an hour in a few places. These will move eastwards, but there is the possibility of further thundery downpours developing overnight."