Motorists are being advised to take extra care when driving.
Rainfall is set to continue today and already a number of roads are closed particularly in Arun and Chichester districts.
These include the A27 between Chichester and Havant, the A29 and A259 at Bognor, the A272 at Petworth and A280 at Long Furlong, Patching.
Insp Phil Nicholas, Road Policing Unit, said: “We are urging drivers to check their speed and drive carefully. Their vision will be hampered by the rain and the spray caused by surface water.
“Throughout last night and today we have been working closely with partner agencies to frequently assess the situation and ensure resources are available where necessary.
“There have been a number of complaints from homeowners who have sandbagged their homes, that fast driving through flood water is causing further damage to their homes. I would warn people to use extreme caution when attempting to go through anything over a couple of inches of water. Do not drive through water that looks too deep to negotiate. If you are in doubt find an alternative route.”