Met Éireann has issued an advisory warning for the whole country, with “bitterly cold” weather expected until next Sunday, December 11.
The National Forecaster has said temperatures will drop below freezing, leaving the country with “widespread frost and icy stretches on roads”.
“Plenty of dry weather is expected but there will be wintry showers at times, particularly in the north and northwest,” according to Met Éireann.
Head of forecasting at Met Éireann, Evelyn Cusack, has warned the public to prepare for harsh conditions as temperatures drop to -6C during the week.
Highest temperatures of 4C are expected in some areas.
Ms Cusack told Newstalk Breakfast it would be bitterly cold this week with hail, sleet, and snow in the northwest forecast for Wednesday night.
This cold spell is brought on by an air mass coming from the Arctic, describing it as a “real reverse” from the very mild November temperatures, she explained.
Met Éireann predicts that “showers will turn increasingly wintry" on Wednesday, with snow likely on high ground.
While the highest risk of snow is in Donegal there could be snow showers at any time over the remainder of the country, added Ms Cusack.
With these sub-zero temperatures, people are warned to expect “widespread sharp to severe frost and ice on untreated surfaces.”
Wednesday’s showers are expected to move southwards over the country overnight and fall as sleet or snow in areas.
The forecaster predicts another “bitterly cold night” on Thursday, with sharp to severe frost and icy stretches expected across the country.
Met Éireann added that the weekend forecast offers “little change”, with “some wintry showers and widespread frost by night expected".
The drastic change in temperature will come as a “big shock” following the mild weather in November resulting from winds coming in from the tropics.
Ms Cusack urged people to prepare in advance of this extreme weather, advising others to go onto the website winterready.ie and to take care on the roads, especially minor roads.