More heavy showers are expected later this afternoon, cuasing further disruption for drivers.
There has been a wide range of rainfall of between 32 to 63mm in 12 hours, with 63mm in Bognor Regis and 55mm in Shoreham.
A flood warning was issued for the River Mole with flooding expected at Charlwood and Hookwood, including Povey Cross Road and Gatwick Airport.
Road closures that were in effect included:
Kerves Lane, Horsham, - tree down and flooding at Amies Mill bridge.
East Mascalls Lane, Lindfield.
A23 closed southbound near Slaugham.
A27 Chichester to Emsworth - diversion along A259 (old A27).
A259 Felpham Way - traffic through.
North Parade, Horsham.
Blakes Farm Road, Horsham.
Fitzalan Road, Littlehampton.
Bernard Road, West Worthing.
Maidenbower Lane, Crawley.
Warninglid Lane, Warninglid.
B2114 Rose Cottage Lane, Staplefield.
Roads that were passable with care but causing long delays:
A259 at North Bersted down to one lane.
Monteswood Lane, Lindfield - river flooded.
Kennedy Road, Horsham.
The Oaks, Burgess Hill.
Ifield Avenue, Ifield - Gatwick stream up, surface water unable to discharge.
Cuckfield Road - A23 to Burgess Hill.
A24 Findon bends southbound.
A29 north junction A27.
A29 Shripney bends.
B2178 West Ashling.
B2233 Yapton - Barnham Road.
Water Lane, Angmering.
Pumps and gully emptiers have been deployed as necessary.
Several Flood alerts have been issued for the area, including:
The River Adur and tributaries from Burgess Hill to Henfield.
Ifield Brook, Upper river Mole, Gatwick Stream, Burstrow Stream and Salfords Stream
Slaugham to Barcomb Mills.
The main problem experienced across the county has been that of surface water flooding affecting many of the main roads.