Met Éireann has issued a Status Yellow low temperature warning for most of the country.
The forecaster issued the warning for 22 counties, with only Dublin, Wexford, Wicklow and Waterford escaping the worst of the cold conditions.
The warning will take effect from 8pm tonight and remain in place until 9am tomorrow morning.
Met Éireann says that it will be very cold tonight, with minimum air temperatures dropping from minus-2 to minus-4 degrees Celsius.
There will also be widespread "sharp to severe" frost with the risk of icy patches.
While there could also be some shallow fog patches inland, it will be less cold near the east coasts.
As for tomorrow, the day is set to be a bright and dry day with good sunny spells.
Following a very cold start, frost will clear and temperatures will recover to range 6 to 9 degrees by the afternoon.
— Met Éireann (@MetEireann) November 17, 2019