Drivers advised to avoid unnecessary journeys
The bad weather has led to another day of disruption across Northern Ireland.
Emergency services again advised people to avoid unnecessary road journeys as snow continued to cause travel problems in several areas.
The snow has been falling again on Saturday evening with the worst affected area being around Downpatrick and south Down.
Public transport has been running on most major routes in Northern Ireland despite the adverse weather conditions.
The International Airport, Belfast City Airport and City of Derry Airport are currently open, however, flights have been disrupted through the day.
All trains are operational, and bus services in Belfast and Londonderry are working, but only on main roads.
Rural transport has been badly affected.
Meanwhile, there are reports of cars being abandoned on the main Newcastle to Ballynahinch Road on Saturday evening.
There was fresh snow overnight with the temperature dropping to -14C in Castlederg, County Tyrone.
Three hundred road service personnel worked through the night, but roads remained treacherous and people are being advised to travel only when necessary.
On Saturday, the Roads Service said snow was still affecting many roads across Northern Ireland.
"In addition, with temperatures sub-zero across the province, there is also the risk of widespread ice on roads.
"Salting and ploughing has been ongoing yesterday evening and overnight, and additional treatment is underway this morning. Private plough operators are also being deployed to provide additional resources."
It said the A6 Glenshane Pass and the A37 Coleraine to Limavady mountain road are open and passable with care, while the M1, M2 and A1 are also passable with care, although overtaking lanes especially are affected by snow or slush.
The speed limit in the Sandyknowes area of the M2 has been reduced to 30mph.
It is understood Meals on Wheels services have been disrupted in south Down, with some people not receiving deliveries for two days.
Worst in 25 years
The snowfall over NI since Thursday has been the worst in 25 years, meteorologists said.
More than 700 schools have been shut and Northern Ireland's airports have been closed at various times.
BBC weather forecaster Cecilia Daly said that similar snowfalls in 2000 were restricted to eastern counties making the current situation "probably the worst in 25 years".
Regional Development Minister Conor Murphy has advised people wanting to help clear footpaths of snow and ice, that they are unlikely to be held liable if there is an accident.
Belfast City Council suspended bin collections on Friday after lorries experienced difficulties in icy conditions. It said that, weather permitting, the bins would be emptied on Monday.
In Londonderry, a gritting lorry driver suffered minor wounds to his cheek on Thursday after snowballs and stones smashed one of the vehicle's windows.
In Glenavy, County Antrim, a gritter came off the road on Thursday night. Roads Service said the driver was tended to at the scene by ambulance personnel and the police. He was shaken but not injured.