A Status Yellow warning for snow and ice has been issued for 18 counties with temperatures set to drop to below freezing overnight.
The warning will come into effect at 6am tomorrow and remain in place until 6pm.
Met Éireann said wintry falls with some accumulations are possible for the five counties of Connacht, along with Cavan, Monaghan, Donegal, Dublin, Carlow, Kildare, Laois, Longford, Wicklow, Offaly, Westmeath and Meath.
It will be dry for much of tonight, but some frost and ice will set in across more sheltered areas and rain will move into the west and southwest, which will be proceeded by falls of sleet and snow, especially over Connacht.
Temperatures will drop to -1C in many areas.
Outbreaks of rain, sleet and snow will become more widespread tomorrow morning and it will be cold with highest temperatures of just 5C.