Motorists are being advised to take extreme care on the roads this weekend as temperatures are set to fall as low as -5C at night with snow and icy conditions expected from this evening.
AA Roadwatch has said road temperatures are below zero on the N2 in Co Monaghan.
The Sally Gap in Co Wicklow is impassable due to icy conditions and motorists are advised to avoid the area.
Meanwhile, recent snowfalls around Letterkenny and Glenties in Co Donegal are causing wet and slippery conditions.
Gardaí have warned people to drive with extreme care in the county.
There are also reports of snow around Dunmore in Co Galway and sleet showers around Ballymote in Co Sligo.
Parts of counties Mayo and Galway have been experiencing heavy snowfalls for several hours and driving conditions are beginning to deteriorate on many roads in the two counties.
Gardaí say conditions could become particularly difficult on minor roads later tonight.
The wintry weather is forecast to hit this evening with snow showers expected in northwestern counties and parts of Leinster giving accumulations of 3cm to 5cm at times.
The accumulations will occur mainly at night time, with occasional thawing likely by day.
Met Éireann is warning temperatures could drop as low as -5C overnight at the weekend.
The Road Safety Authority has urged drivers, cyclists and pedestrians to be extra vigilant.
The RSA is advising people to watch out for black ice, use dipped headlights, leave plenty of space to brake and be prepared for breakdowns.
In Britain, up to 15cm of snow fell yesterday; the earliest snow for November in almost two decades.