A Met Office warning for heavy thundery rain across Sussex has been extended to include all of tomorrow (Friday September 16).
The yellow warning is in place for today from 2pm but now carries on right up to 8pm on Friday.
The main concern is for the amount of rain that might fall in a short space of time.
However, there is also the risk of frequent lightning.
The chief forecaster says: “A front coming from the Atlantic will merge with warm, unstable air over the country to bring the risk of 30-40mm in the hour in places and more than 50mm in a few hours.
“Whilst the vast majority will have much less than this, it could cause disruption, especially if heavier bursts coincide with urban areas.”