Motorists are being warned to take extra care on the roads this morning.
A Status Yellow Snow and Ice Warning remains in place for the entire country until midday.
Severe frost and ice will be an issue on untreated surfaces according to Met Éireann, while snow will likely affect those travelling on higher ground.
Drivers should slow down in affected areas, as stopping distances are about ten times longer on icy surfaces.
Jonathan Byrne from AA Roadwatch has this advice:
"Try to stick to national roads or motorways if possible as secondary and local routes are less likely to be treated," he said.
"Something that can't be understated is to allow yourself plenty of time for your journey, now this involves the adequate time to de-ice your car beforehand and clearing your car of ice or snow," he said.
Met Éireann has forecast scattered outbreaks of rain and drizzle today, with afternoon temperatures of 6C to 10C.
Tomorrow is expected to be largely dry with sunny spells, and after a chilly start, temperatures will rise between 7C and 9C in the afternoon.
The rest of the week is set to be unsettled, with scattered showers and windy spells likely most days. Frost is also expected on Tuesday night, along with some showers.
Conditions in parts of Britain are far worse than here, with England seeing its coldest night of the winter so far as temperatures dropped to minus 11.7C overnight.
In Scotland, a low of minus 12.6C was seen in the Highlands, although it was a few degrees off the minus 15.4C seen there on Thursday.
In Northern Ireland, the lowest temperature recorded was minus 2.6C in Katesbridge, Co Down.