A Flood Alert has been issued by the Environment Agency for the Ifield Brook, Upper River Mole, Gatwick Stream, Burstow Stream and Salfords Stream.
The agency says flooding is possible for the Ifield Brook, Upper River Mole, Burstow Stream and Salfords Stream including Ifield, Lowfield Heath, Charlwood, Hookwood, Bewbush, Furnace Green, Maidenbower, Crawley, Horley, Copthorne and Salfords.
These areas are likely to flood into the evening and over night tonight. Low lying land and roads will be affected first. The Environment Agency is warning residents to be prepared.
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Friday afternoon's forecast for the west of the region
Friday afternoon's forecast for the east of the region