Heavy rain overnight has left many areas flooded. West Sussex has been badly hit - the local fire service received around 150 calls.
Staff at Worthing Hospital had to pump out water from the basement. And although it did not have to evacuate, emergency cases are being diverted to Brighton and Chichester. Elsewhere people have reported flood water reaching up to a metre in height.
Littlehampton, Bognor Regis, Angmering and Rustington are the worst affected areas.
A rescue centre was set up in the Sportsdome at Littlehampton Swimming Centre for some families who had to leave their homes because of the flooding. The centre is being run by Arun District Council with support from the Red Cross Fire & Emergency Support Service.
The fire service reported that the biggest impact was on Littlehampton seafront where a number of basement flats were flooded to a depth of up to four feet.
There are no reports of any injuries, but people are being urged to stay out of floodwater due to the dangers of lifted manhole covers and water contaminated with sewage.
The Environment Agency, Police and Southern Water are helping to deal with the flooding operation.