Met Éireann has issued a status yellow snow-ice warning for 20 counties.
The warning comes into effect at 7am tomorrow morning and will first affect parts of Munster from 7am until 4pm. It will then spread and affect counties in Leinster, Connacht and Ulster.
As well as all of Connacht, these are the counties affected: Connacht, Cavan, Monaghan, Donegal, Dublin, Kildare, Laois, Longford, Louth, Wicklow, Offaly, Westmeath, Meath, Kerry, Limerick and Tipperary.
Patchy accumulations of up to 3cm of snow are due, especially on high ground, but small amounts at lower levels also.
However, the snow is not set to last – rain will follow, clearing any snow away.
It will be cold and breezy today, with sunny spells and scattered wintry showers. Highest temperatures of 3C to 6C are expected.
There will be a widespread sharp or severe frost and icy patches tonight. Fog will develop and will become dense overnight in parts of Leinster, Connacht and Ulster. Temperatures will drop as low as -3C.