Many areas of the county were beset by flooding following heavy rainfall overnight on Tuesday.
Bognor, Arundel, Crawley, Bexhill, Uckfield and several other locations in Sussex experienced as much as 30mm of water.
The River Ouse, Uck, Cuckmere and Arun already had high water levels from Storm Bert and Storm Connall has caused them to break their banks into Wednesday morning.
A dozen yellow food alerts were issued on Tuesday evening and three red flood warnings issued on Wednesday by The Met Office.
On Tuesday evening, The Met Office predicted rain to reach parts of southern England overnight on Tuesday, becoming “persistent and heavy” in places for a time.
The warning also said that “flooding of a few homes and businesses is likely, as is some interruption to power supplies and other services”.
Numerous roads, including in Worthing, West Hoathly, Aldwick, Horsham and Steyning have been closed.
Water on the tracks caused severe delays for Southern Rail trains, with no trains running between Oxted and Uckfield and none between Redhill and Tonbridge. The Gatwick Express suspended its trains until 13.39pm.
Fish Lane in Bognor became submerged with one vehicle stranded in the water.
Very little rain is now expected until the weekend, with river levels expected to drop from Wednesday afternoon.
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