The Met Office has issued a thunderstorm warning for a wide area including Brighton and Hove.
The “yellow” warning comes into effect from 8pm this evening (Sunday 4 September) until 4am tomorrow, with the weather potentially causing some localised disruption.
The official forecaster said that there was a good chance that driving conditions would be affected by spray or hail.
And, the Met Office said, there would probably be some damage to buildings and structures from lightning strikes and gusty winds.
Flooding of homes and businesses is possible and there could be delays to rail services.
Forecasters also said that some short-term loss of power and other services was possible.
The Met Office said that the heavy showers and thunderstorms were expected to develop across south west England this evening and move north across parts of Wales and Northern Ireland.
They are expected to clear during the early hours while a separate area of thunderstorms is likely to develop across central southern England in the late evening, moving north overnight.
About an inch of rain – or 20mm to 30mm – could fall within an hour in places while others may not see much rainfall at all.
Forecasters said that frequent lightning, hail and local gusty winds could accompany stronger thunderstorms but these look more likely in the south west.
A wet week is in prospect, with further rain forecast from late morning Tuesday until the early hours of Friday. Tuesday is also expected to be windy.
