Commuters faced a frosty, foggy and freezing cold morning on Thursday as temperatures dropped to minus 5 country overnight.
Met Éireann has warned of poor driving conditions on Thursday as two weather warnings remain in place.
At 7am there was -5 temperatures recorded at the weather station in Casement aerodrome in Dublin and subzero temperatures recorded at weather stations right across the country.
An orange alert, the second highest warning, for dense fog across Ireland is in place until midday.
The national forecaster said the overnight frost and fog would be slow to clear and could linger in some places all day with temperatures reaching a maximum of 2 to 4 degrees.
Elsewhere, it will stay dry with some sunny spells and temperatures are expected to range between 6 to 9 degrees.
The low temperature warning for Leinster, Munster and Connacht will remain in place until 9am.
Forecasters warn hard frost and icy stretches will form under the clear skies later on Thursday night with some dense fog. Severe frost is expected across Leinster, Connacht and Ulster with temperatures falling again to minus 5 degrees.
AA Roadwatch said traffic is heavy in Maynooth, Co Kildare in both directions between Main Street and M4.
It said the Ballycahill and Thurles Rd in Co Tipperary is closed this morning due to an overturned vehicle.
Friday is set to be frosty and foggy once again with highest temperatures reaching 6 to 10 degrees.
However, it will stay colder in areas where fog persists through the day and some showers are predicted to hit the south and south west coast.
The start of the weekend will be cold and dry with temperatures dropping to minus 1.
Sunday will be windy and a risk of rain over southern and western coastal counties.