Icy conditions are continuing to cause disruption with motorists urged to take care on the roads.
A yellow weather warning for ice and snow has been in place.
A number of schools have been closed because of the weather conditions.
At Belfast City Airport, London and Amsterdam flights have been disrupted. At Belfast International Airport, a flight from Amsterdam has been cancelled.
An inbound flight from Lanzarote has been delayed for five hours.
Bus services across Northern Ireland have also been affected by the icy conditions.
Bus services into and out of Coleraine, Ballymoney, Ballymena, Ballycastle and Armagh have been disrupted. Ulsterbus will not be serving Greenisland until further notice.
RPU responded to a report of a car on fire on the A1 this morning. The driver had placed a blanket on the engine overnight and forgotten to remove it. Thankfully nobody was hurt although the driver was more than a little embarrassed for the trouble caused! pic.twitter.com/Var4A7jPxw— PSNI Road Policing (@PSNITraffic) December 11, 2017
Police are warning drivers of very icy conditions in Swatragh, where the Killygullib Road remains closed after a lorry jack-knifed.
The Carnmoney Road in Eglinton has also been closed because of black ice.
The Woodburn Road in Carrickfergus is closed in both directions near Woodburn Dam due to icy conditions and ice is also causing problems at the Carrowreagh and Greengraves roads in Dundonald.
Police are advising drivers to avoid the Montiaghroe Road between Kesh and Castlederg following an accident and also the Coleshill and Drumcose roads in Enniskillen.
Translink said all Belfast services were operating, but warned that buses may be late due to the poor road conditions.
Most trains are unaffected and running on time.
However, Londonderry passengers can expect delays to their services because the weather has led to a speed restriction on the line.
Temperatures plummeted to below freezing in some areas of Northern Ireland overnight, with -10C recorded in Katesbridge, County Down.
There has been disruption in Northern Ireland since Friday when wintry showers brought the first flurries of snow.
The snow in London continues to cause disruption to flights with a number of cancellations to and from Heathrow at George Best Belfast City airport including the 07:45 and 14:15 arrivals and the 07:10, 08:35 and 15:05 departures, check with your airline for updates— BBCNI Travel (@BBCNITravel) December 11, 2017