Pictures and video footage showing two funnel clouds over Selsey have appeared on social media.
A tornado warning has also been issued for the south east and the Isle of Wight.
Pictures of the freak weather event are continuing to appear on social media. Jenni Purple shared the shocking footage on Facebook and Twitter while Meryn Woodland sent photos to The Chichester Observer.
The Met Office has issued a yellow weather warning of thunderstorms across the south east.
The warning said: "There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes or hail.
"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."