A widespread sharp to severe frost will bring icy patches and dangerous driving conditions tonight and tomorrow .
There will be some wintry showers of sleet or snow at first tonight, but they will become more widespread from the north later in the night.
Temperatures could plunge as low as minus 4, Met Eireann says.
Some patches of mist and freezing fog will form too, adding to the potential danger for road users.
And freezing fog and icy roads will make driving conditions treacherous on Monday morning as the nation returns to work.
Met Eireann said the cold snap will continue until Wednesday night.
That will mean severe night frosts and a risk of freezing fog, particularly tomorrow night.
There will be more sleet and snow at times but despite the biting winds, there will also be dry, bright conditions with sunny spells.
Tomorrow night will be mostly dry but very cold and icy with some pockets of freezing fog developing overnight, as the winds drop in the hours before dawn.
Frost and fog may linger in some areas throughout the day with afternoon temperatures of 1 to 4 degrees C.
Western coastal counties are most at risk for rain, sleet and snow on Monday night but Tuesday’s morning commute to work could be icy over most of the country.
Today road temperatures were below zero on a number of routes as Eircom crews worke to restore service to customers following Storm Rachel.