End in sight to Arctic conditions
Overnight temperatures are to plummet as low as minus 15C in parts this week but Christmas will be dampened by wind and rain from the Atlantic, pushing the thermometer up, forecaster say.
The mercury dropped bitterly low on Sunday night, with temperatures at Castlederg, Co Tyrone, falling to a bone-chilling minus 18C.
Motorists have been urged to drive with extreme care as icy conditions persist, but road chiefs said fresh salt shipments would arrive by Wednesday.
Met Eireann said the end is in sight to the Arctic conditions, with temperatures as high as 10C by Christmas Day.
Forecaster Pat Clarke said: "The good news is we are expecting the weather to get milder during Christmas Day. What's going to happen is a band of wet and windy weather is going to sweep in from the Atlantic. That will bring rain."
Mr Clarke said sleet and snow may fall during Christmas Day as the Atlantic system meets the cold air.
Snow remains a risk in the east coast as showers linger in the Irish Sea, with parts of Tipperary, Waterford and east Cork also under threat. Temperatures up until Wednesday night will be as low as minus 15C, particularly in the north-west.
The rest of the week is expected to be dry but cold, with overnight restrictions on water in Dublin to be lifted by Thursday.
Christmas week will see temperatures of up to 9C, with cool nights.
The National Roads Authority (NRA) said it has 8,000 tonnes of salt left, but 4,000 tonnes are due to arrive on Wednesday and every two days thereafter, bringing reserves up to 25,000 by Christmas week.