A snow and ice warning is in place for the country, which is valid until 11am tomorrow.
Temperatures are set to fall to -2C in places.
Met Éireann is forecasting that rain and sleet will extend from the west, turning to snow at times as it encounters colder air further east and north.
There could be up to 3cm of snow in Ulster, north Leinster and parts of east Connacht.
Met Éireann also says there could be frost and ice on untreated surfaces.
Motorists around the country are advised to drive with care.
Particular care is needed on secondary roads around Carlow town, Cavan town, Letterkenny, Castlebar and Navan, according to AA Roadwatch.
It also says that drivers should take care around Ballina, Crossmolina and Ballymote.
MEATH: The Slane/Kells Rd (R163) is particularly icy this evening. Take extra care if you are travelling this route. http://t.co/qvBPcgPvrc
— AA Roadwatch (@aaroadwatch) January 19, 2015