The Met Office website shows sleet for Lewes from 3pm this afternoon (Tuesday January 22) followed by light snow from 9pm but clearing by midnight.
The temperature for today should be around 1-2C, although it was -1.5C at 9am and the minimum is -3C.
Forecasters said rain or sleet along the coast will move inland across Hampshire, turning to snow and possibly giving slight accumulations.
Elsewhere there will be some clear spells but also isolated sleet or snow showers.
Tomorrow the forecast is for cloudy weather and 0C temperature in Lewes.
Across the region, forecasters predict there will be widespread ice at on untreated surfaces, mainly dry with some bright intervals. Maximum temperature 2C.
Thursday is looking overcast for Lewes with sleet on Friday and Saturday, turning to light snow in the early hours of Sunday morning.