A new Status Yellow snow and ice warning has been issued with snow expected in many areas across the country.
The warning will come into force at 3am on Thursday morning and is due to remain in place until 11pm that evening.
Met Éireann is warning drivers to take care – with the cold snap set to bring hazardous driving conditions and poor visibility.
The forecaster said it could also disrupt other forms of travel.
It said, rain, sleet and snow will spread northwards across the country later tonight (Wednesday night) and during Thursday accompanied by strengthening easterly winds.
Accumulations of snow are expected in many areas along with icy conditions.
The forecaster said, “outbreaks of rain, sleet and snow in the southwest will extend into parts of Leinster this afternoon and evening.”
It will be brighter and drier elsewhere with sunny spells and just isolated showers.
Tonight will be cold and frosty with temperatures falling to -2C, while Thursday will be “very cold with rain sleet and snow spreading north-eastwards to most areas”.
There will be poor visibility and very hazardous driving conditions and, in the afternoon, sleet and snow will continue over Ulster, Connacht and north Leinster.
It will turn mainly to rain and sleet further south.