Warnings to motorists are continuing amid icy conditions and fog on roads across Northern Ireland, as temperatures look set to fall even further.
Some more snow showers are still possible too, particularly on the north coast.
Temperatures will struggle to climb above freezing and could plummet to as low as minus 8 Celsius by nightfall, according to the Met Office.
John Hutchinson, a forecaster with MeteoGroup, said: "I think it will be the coldest night of the year for many places.
"There will be some patches of freezing fog that will be another hazard."
With more predictions of patches of freezing fog as well, festive travellers face further disruption at airports as they try to get away before Christmas Eve.
Belfast International Airport spokeswoman Deborah Matchett has advised passengers expecting to catch a flight to check with their airline.
"We probably will have some knock-on delays again from England which has been quite badly hit, so there will probably still be some knock-on delays from the London airports and probably Liverpool and Manchester," she said.
Southern England has borne the brunt of the Christmas cold snap with temperatures falling to below minus 10 Celsius.
On Tuesday night, two women, aged 78 and 70, were killed in a crash after a coach overturned in treacherous conditions in Cornwall.
Forty-seven people were left injured when the coach ended up on its side near Penzance as it carried passengers back from a trip to see a Christmas lights attraction.
© UTV News