The A285 is blocked both ways due to fallen tree between Dye House Lane and Selhurstpark Road, the AA said. Traffic sensors indicate the closure is south of Duncton.
There are also delays of six minutes and increasing on Crockhurst Hill eastbound between A27 Arundel Road (Coach And Horses) and A27 Sompting By-Pass.
The average speed is 15mph.
There are no major delays being reported on the railway network in the county.