Some schools were closed on Thursday, including Ticehurst and Flimwell and Netherfield primary schools.
Several key routes were affected by the weather on Wednesday evening, including the A23 and A27, Sussex Police said.
Officers said there had been “multiple collisions” in parts of Brighton and Hove.
Callers to BBC Radio Sussex described “chaotic” and “nightmare” scenes on Wednesday and complained many roads and pavements lacked grit.
Eve from Woodingean said it took more than six hours to get home on Wednesday night, usually a 20-minute journey.
Brighton and Hove City councillor Trevor Muten apologised for the “difficulties” motorists faced in and around the city.
Most roads across South East England were running as normal on Thursday morning.
“Surfaces have been left wet and cold following Wednesday evening’s rain and snow,” wrote the Met Office on its website.