Temperatures across Ireland will plunge to as low as -3C over the next two nights.
Met Eireann is forecasting "widespread frost" on what will be a chilly Sunday night.
A predicted weather map shows overnight temperatures dropping to -2C in the south and -3C in the west.
A forecaster said: "Dry, cold and calm tonight with overnight lows of -3 to 0 degrees; coldest further south under clearer skies.
"A widespread frost will set in, along with some icy stretches. Mist will thicken into fog in parts too."
Monday is expected to be a dry day across the country, with frost and fog clearing during morning.
The south will see the best of sunshine, but it will be a cold day with highs ranging from 5C to 8C.
Overnight temperatures will range from -3C to 3C, with the Midlands set to experience the coldest condition, according to a predicted Met Eireann map.
The forecaster said: "Monday night will be dry, apart from the odd coastal shower in the northwest.
"Cloudy at times in Connacht and west Ulster, but long clear spells prevailing elsewhere.
"Lows of -3 to +3 degrees Celsius, coldest in the east and south under clearer skies, with a sharp ground frost forming in these parts, and icy patches on untreated surfaces.
"Light southerly breezes, will be fresh to strong and gusty on Atlantic coasts."
