A snow and ice warning has been extended until midday tomorrow as temperatures are expected to drop to minus six degrees in the coming days.
Met Éireann has issued an orange weather alert, the second highest warning.
Up to eight centimetres of snow is expected to fall in counties Donegal, Leitrim, Mayo and Sligo tonight and tomorrow.
The Road Safety Authority is warning all drivers to slow down as the cold snap continues.
Three separate collisions are currently affecting traffic on the M7 Limerick/ Dublin Rd between 23 Moneygall and J21 Borris in Ossory, while snow and ice is a problem in counties Roscommon, Donegal and Sligo.
Widespread wintry shwrs will continue through the afternoon & evening, becoming confined to northern areas later. Temperatures of just 2-5C— Met Éireann (@MetEireann) January 14, 2016
However, Joanna Donnelly from Met Eireann says parts of Leinster will not escape the severe cold snap.
She said: "The showers are going to get heavy, possibly merging into longer spells of sleet and snow over the course of tonight and early morning.
"And in the North it'll probably be extended further into the afternoon too, because the showers will continue there.
"The wintry showers will be widespread for the rest of the afternoon and for the evening. In fact there is a rather large blob heading towards Dublin as we speak."