Met Éireann has issued a Status Yellow warning for snow and ice in Connacht and counties Donegal and Cavan.
The warning will come into effect at 6pm this evening until 11am tomorrow morning.
The forecaster says temperatures will drop tonight to between minus 1 and plus 2 degrees.
Gardai in Donegal have issued a warning for drivers and road users as temperatures are set to drop.
It is being advised to leave extra time for journeys, drive with caution, give your car a general once over and pay particular attention to tyres ensuring that they are roadworthy and have a good grip.
Motorists are also advised to check car lights and make sure bulbs are all in working order.