The Glenshane Pass at lunchtime on Wednesday
Motorists in parts of Northern Ireland have faced treacherous conditions following snowfalls.
Police said the worst affected roads were in counties Londonderry, Tyrone and Down.
Cars were stranded on the Glenshane Pass near Dungiven, however, it is said to be passable with care. Conditions were also bad on the M1 near Dungannon.
John Hammond of The Met Office said Northern Ireland has been experiencing its coldest October for many decades.
He said Tuesday's maximum daytime temperature was the lowest since 1934.
"It will be cold and raw again today. People should take care and stay close to the weather forecasts."
Colin Brown from the Roads Service said it had 120 gritters out to cover 7,000km of road in three hours.
"Without a shadow of a doubt the winter is upon us," he said.
He said that there have been instances of gritting in the run-up to Halloween in the past, but that this was the first instance he was aware of which involved the use of snow ploughs.