Chichester will start overcast changing to mist by late morning, with highs of 12 degrees Cesius and a low of seven, the Met Office said.
Horsham has a yellow weather warning for fog in place today. Temperatures will reach a high of 13 before dropping to seven.
Worthing starts overcast changing to sunny intervals in the afternoon with highs of 11 and a low of eight.
Brighton is also overcast but the sunny intervals will arrive slightly earlier – by lunchtime. Temperatures will peak at 11 before dropping to seven overnight.
Hastings will start misty before changing to overcast by late morning with highs of ten and a low of seven.
Eastbourne is overcast today changing to heavy showers by nighttime with a high of 11 and a low of seven.