Met Éireann has warned that temperatures could drop as low as -2C as Status Yellow snow and ice warnings are in effect for 11 counties.
Sligo, Leitrim, and all of Ulster are under the snow and ice warnings until midday, with wintry showers of hail, sleet and snow expected.
Met Éireann said that there will be some modest accumulations in places, especially on high ground.
The forecaster warned motorists to expect hazardous travelling conditions and icy stretches.
The UK Met Office warned that wintry conditions overnight will bring some icy patches and lying snow in places.
Nationally, it is expected to be rather cold with frost and icy patches slow to clear.
The showers will die out over Connacht and Ulster with highest temperatures struggling at 3 to 7 degrees in a cold northerly breeze.
Crisp sunshine will break through this morning with plenty of clear and dry weather for this afternoon and evening.
In the UK, blizzard conditions are possible in parts of north-east England where an amber warning for snow is coming into force, the Met Office said.
Sleet and snow showers will continue to hit UK coasts overnight, with worst-affected areas set to face disruption to travel and potential power cuts, the forecaster said.
Additional reporting PA.
