However it may become increasingly cloudy as the day goes on, with some outbreaks of rain in the north of the county from the late afternoon.
It is likely to remain very warm in the south of Sussex and by the coast, according to the Met Office.
Tomorrow morning is set to be cloudy with some light rain.
However the rest of the day will be mainly dry with clouds breaking to give occasional sunny spells, the Met Office said.
The maximum temperature tomorrow will be 23 degrees.
The South East Coast Ambulance Service is warning people to take care in the sun today and to make use of alternatives to calling 999 when it is not a serious emergency.
The service received five 999 calls a minute at some points last Saturday, which was the hottest day of the year so far.