Gritters have been out across Dorset to treat roads after 10cm (4in) of snow fell in one hour in the west of the county.
The snow came down early on Friday and driving conditions became difficult on the A37, A354 and C12.
More heavy snowfall is due on Saturday across southern England, with South West Trains revising its timetable.
Dorset County Council said it had sent out its salting fleet to treat its 680-mile (1,094km) "winter network".
It said the gritting of a number of "community links" connecting villages has also taken place.
'Conditions are severe'
"The council's 26 gritters will be prepared to salt roads and fit ploughs to clear snow depending on the severity of wintry showers overnight," a Dorset County Council spokesperson said.
"Motorists are advised to take extra care and not to travel unless absolutely necessary if conditions are severe."
Andy Pitt, managing director of South West Trains, said: "We know that what our passengers want most is certainty about when and how they are going to get to their destination.
"The revised timetable we have in place for Saturday will help to ensure we make best use of our resources to deliver the most robust service we can for passengers should the forecasts prove accurate."
Rail passengers have been advised to go to the South West Trains website for more information.