The Met Office is warning of thunderstorms which are expected to develop in the English Channel on Wednesday night and move east during Thursday morning.
Whilst many thunderstorms will remain offshore, some may also develop over southeast England.
10-15 mm of rain is likely to fall across Kent and the South East fairly widely with isolated accumulations of 25-30 mm, mainly over 3 hours on Thursday morning.
However, a few places may see these higher accumulations fall in an hour, particularly towards the south coast.
Frequent lightning, hail up to 3 cm in diameter and squally winds are additional hazards.