The Met Office has issued a severe weather warning as snow coupled with overnight icy temperatures make driving conditions treacherous.
Abandoned cars hampered the rescue effort
Up to 400 cars were abandoned across Gloucestershire after 3in (8cm) of snow fell in three hours on Monday.
Police used 4x4 vehicles to reach the last stranded motorists by midnight.
Forecasters predicted a frosty Tuesday morning for most inland areas of the UK, but milder temperatures towards the end of the week.
Western Scotland, Northern Ireland, Wales, the far west of northern England and south-west England were predicted a cloudy day with showery outbreaks of rain or sleet.
Accidents were reported on many of Gloucestershire's main roads on Monday night.
Abandoned vehicles on country roads hampered efforts to send gritters to remote areas, and some gritters became trapped.
The worst affected areas were Cirencester, Stroud and the south Cotswolds.
By Tuesday morning the only road in the county which remained closed was the A419 between Stroud and Cirencester at Cowcombe Hill, which was blocked by abandoned cars.
All other roads were passable with care.
Elsewhere, motorists in Wales were warned of black ice after it was blamed for 10 accidents in Carmarthenshire.
By early Tuesday morning snow was falling over high ground in south-west Scotland and Northern Ireland.
Elsewhere, snowfall was likely on higher ground in the North East and some coastal areas, but rain was expected to spread across the country.
This, coupled with cold air feeding in from the west, could lead to widespread ice, said a Met Office spokesman.
BBC correspondent Jon Kay said the snowfall in Gloucestershire had "taken an awful lot of people by surprise".
"It raises questions about how prepared we are as a nation to deal with extreme weather," he said.