Chichester will reach a high of 2 degrees Celcius before dropping to 1 overnight. The city will see sunny intervals changing to cloudy by lunchtime, the Met office said.
Worthing will be overcast and 2 degrees throughout the day.
Horsham will start cloudy, changing to fog by nighttime, staying at 2 degrees.
Brighton and Hastings will be cloudy, reaching 2 and 3 degrees respectively before dropping to 2 degrees overnight.
Eastbourne will hit a high of 2 before dropping to 1, starting with sunny intervals changing to cloudy by the afternoon.