Ireland is facing "widespread frost" before temperatures plunge to as low as -4C on Sunday night.
Met Eireann is forecasting a chilly Friday, which will see mostly sunny spells and a few showers.
Overnight is set to be bitterly cold, with a risk of dense fog and icy patches in some areas. Night-time temperatures will be as low as -2C.
A forecaster said: "Dry in most areas today, with sunny spells, but a few scattered showers will occur, mainly in eastern and northwestern coastal areas.
"Cold, with maximum temperatures of 6 to 9 Celsius. Winds mostly moderate north to northwest, fresh to strong along eastern and southern coasts.
"Tonight will be mainly dry, with clear intervals, but very cold, with widespread frost and a risk of icy patches.
"Minimum temperatures minus 2 to plus 2 Celsius. As winds slacken, fog patches will develop, with the risk of some dense pockets."
Saturday will be extremely cold, with afternoon highs ranging from 4C to 8C.
And while Sunday will be slightly warmer, an icy night is in store as lows will range from 0C to -4C.
The forecaster said: "Mostly cloudy at first, with some patchy rain and drizzle in places, but becoming bright and mostly dry during the day, with sunny spells developing.
"However, a few scattered showers will occur along northern and eastern coasts.
"Cold, with maximum temperatures of 6 to 9 Celsius, in mostly moderate northerly breezes, fresh on exposed coasts.
"Sunday night will be mainly dry and clear, but very cold and frosty, with a risk of icy patches. Mist and fog patches also. Minimum temperatures 0 to -4 Celsius."
