A status yellow weather warning will remain in place until 10am this morning.
Very cold temperatures mean icy patches and widespread frost across the country while Met Éireann forecast highest temperatures of 3 and 7 degrees.
Freezing mists and fog will clear during the morning.
Icy showers are expected in Ulster, Connacht and Munster whilst conditions will remain mainly dry in the east.
Persistent rains are predicted for later in the day along the west and southwest coasts.
It is forecast that showers may develop into sleet and snow.
AA Roadwatch reports icy road conditions this morning in Wicklow, Wexford Town, Letterkenny and Kilkenny.
Elsewhere, traffic expected in Kilkenny due to filming.
Works are taking place on the N24 Waterford-Limerick Road and traffic is down to one lane.
Ongoing works on the N65 Lehinch-Portumna Road approaching Portumna Bridge means a stop and go system is in place and motorists can expect delays.
Motorists are warned to take care of icy patches on secondary roads.