The Met Office issued a yellow warning for ice across Northern Ireland on Friday morning.
The warning was in place until 10:00 GMT.
Wintry showers were expected particularly in the north and west.
BBC NI's Geoff Maskell said the weather warning was primarily for "untreated surfaces."
"It was a very difficult night for gritting.
"We've had bands of showers coming in so as soon as the salt is on the road it's being washed off again."
However, Geoff had some good news: "Increasingly we're going to see more sunny spells as we go through Saturday."
Police said three roads between Limavady and Coleraine are now passable with care following earlier snow showers.
The Broad Road, Windyhill Road and Dunhill Road had been blocked.
The Baranailt Road in Claudy is also now passable with care.
"Motorists travelling on these roads are advised to exercise extreme caution," police said.