A status yellow snow and ice warning is in place across the entire Northern Sound region this evening.
It affects both Cavan and Monaghan from 6pm today until 11am tomorrow.
Temperatures are set to fall as low as minus four degrees, with wintry showers, frost and icy patches expected.
Drivers are being urged to avoid unnecessary travel, with hazardous conditions and poor visibility forecast.
Cathal Nolan, founder of Ireland's Weather Channel, says the low temperatures are leading to dangerous road conditions.
Brenda Bolger from Bolger's Motoring School says extra care is needed and has this advice.
Meanwhile, as the cold snap grips the country, people are being urged to check in on elderly or vulnerable people.
The charity ALONE says that increases the risk of falls and illness among older people.
CEO Sean Moynihan says it can be a hard time of year.
Separately, the UK Met Office also issued weather alerts for counties in Northern Ireland, with the forecaster warning that "snow and ice has the potential to cause disruption to travel in places throughout the weekend and into Monday morning".
A snow and ice warning for counties Antrim, Armagh, Down, Tyrone and Derry is came into effect at midday and expires at midday on Monday.
