Ireland should button its collective collar as the cold snap brings a risk of snow showers to all parts of the country, Met Éireann said today.
The north of the country has already seen significant snowfall, although the PSNI has said that all roads are "passable with care".
The roads service in Northern Ireland has gritted all major routes, but motorists have been advised to slow down and leave extra time for journeys.
A spokeswoman for Met Éireann
The Carrickfergus, Newtownabbey and Ballyclare areas are reported to be particularly affected, and driving conditions are difficult on the Upper Springfield Road in west Belfast, where a number of crashes have been reported.
Snow showers have also been reported in parts of Connacht and as far south as Tipperary.
A spokeswoman for Met Éireann said that strong breezes may continue to spread the showers south and further inland.
"Ulster and north Connacht are at the most risk," she said. "But there could be significant snowfall in many places: Donegal, west Ulster, Connacht, northern parts of Leinster, and some midland areas."
The cold weather is expected to continue for the rest of the week, with night time temperatures dipping as low as -2 in areas with no snow cover, and as low as -7 in areas that have experienced snowfall, she added.
Icy conditions are expected in most parts of the country tonight, and the AA has advised motorists to exercise extra care, particularly in the north and north west of the country.