The yellow alert has been issued for the south coast – with Portsmouth in the firing line.
The Met Office said heavy rain and thunderstorms are likely to roll in from midnight, with the warning remaining in effect until 10am on Saturday.
A spokesman for the Met Office said: ‘There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds
‘Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services.
‘Spray and sudden flooding could lead to difficult driving conditions and some road closures.
‘There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost.’
Rain is expected throughout the weekend, with temperatures reaching a high of 17 degrees tomorrow.