It has warned of widespread sharp to severe frosts with some showers of hail, sleet and snow – mainly near coasts – and freezing fog at times.
The forecaster said low temperatures could lead to treacherous conditions on paths and roads, travel disruption, burst water pipes and damage to engines.
There is increased risks to vulnerable members of the community, Met Éireann said.
Meanwhile, a Status Orange low temperature and ice warning for Ireland will come into effect at 5pm, valid until midday tomorrow, with temperatures likely to fall below -5 degrees in many areas.