There is traffic on the A27 eastbound approaching Chichester.
Delays are also expected in patches heading in both directions on the Chichester Bypass.
Roadworks on the A27 in both directions between the A280 and A24 north are also taking place until 11pm on Wednesday, November 17.
There is a build-up of traffic eastbound on the Shoreham Bypass by Stoned Road.
Heavy traffic has been seen on a number of roads near Brighton, including on the A27 westbound by Devil’s Dyke Road, the A270, A2038, A293 and northbound on Dyke Road Avenue.
Delays are expected on the A264 in both directions passing Littlehaven near Horsham.
There is also traffic heading north on the A2290 in Eastbourne.