The county is set for another hot September day in a summer resurgence after an August washout, the Met Office said.
Temperatures are soaring to the mid to high 20s, reaching 27 degrees Celsius in Horsham.
And people will need to slather on the sun cream as the bright sunshine is set to persist all day.
Temperatures will drop slightly overnight but will remain in the high teens.
Tomorrow is set to be warm again before temperatures cool off towards the end of the week.