Tonight is expected to be one of the coldest of the year, with some parts of the country experiencing lows of minus six degrees.
A yellow weather warning remains in effect until tomorrow morning.
Dry & v cold. Min -2C to -6C; icy stretches on untreated roads. Patches of freezing fog in calm conditions. Frost slow to clear 2moro.— Met Éireann (@MetEireann) December 28, 2014
A Met Eireann spokesperson said: "It is going to become extremely cold after dark this evening."
"There will be widespread severe frost and icy patches will form also."
KERRY/ CORK: Icy conditions on N22 Killarney/ Cork Rd between Killarney & Ballyvorney. Drive with extreme care. http://t.co/qvBPcgPvrc— AA Roadwatch (@aaroadwatch) December 28, 2014
Dense patches of fog will also form in the calm conditions, leaving treacherous stretches of road in many parts of the country.
The fog will linger well into the morning, and may not be fully cleared until the afternoon tomorrow.
KILDARE: Patches of ice on the Kildare/ Allenwood Rd (R415) and then again on the Allenwood/ Clane Rd (R403). http://t.co/qvBPcgPvrc— AA Roadwatch (@aaroadwatch) December 28, 2014
The mercury fell well below freezing in most parts of the country last night, and gardai to advised motorists to reduce their speed and leave increased braking distance between vehicles.
Tomorrow night is also expected to be cold - with temperatures as low as minus three degrees predicted.
A southerly air flow is expected to hit Ireland on Tuesday, which should see overnight temperatures rise to above freezing for the first time since Christmas in many parts.
Rain is expected to usher in 2015, which will mean no frost is expected overnight on Wednesday.
New Years day will start out mainly dry, however rain will spread to most parts by the afternoon.