Met Éireann has issued a snow and ice warning for five counties, while the UK Met Office has issued a separate snow-ice warning for all of Northern Ireland.
The Snow-Ice warning was issued for Cavan, Donegal, Monaghan, Leitrim, and Sligo. The warnings are valid from midnight on Wednesday until midday on Thursday.
Met Éireann warned of wintry showers of hail, sleet and snow, with some modest accumulations in places, especially on high ground. Hazardous travelling conditions and icy stretches are expected in these counties.
Meanwhile, the UK Met Office has also issued a Yellow Snow and Ice Warning for Antrim, Armagh, Down, Fermanagh, Tyrone, and Derry.
The forecaster said there would be wintry showers on Tuesday night into Wednesday, which will bring some icy patches and lying snow in places, leading to possible travel delays. This warning is also valid from midnight on Wednesday until midday on Thursday.
Overall, Met Éireann said it would be cold through midweek with wintry showers possible, especially in Ulster and north Connacht. Milder Atlantic air returning by Friday.
Wednesday
Cold tomorrow, Wednesday, with sunshine and scattered showers, some of them wintry with hail and sleet. Some snow showers are possible too, mainly over higher ground in the north and northwest. Highest temperatures of just C3 to 7C, and feeling even colder with an added wind chill factor from moderate to fresh north to northwest winds, stronger near exposed coasts.
Wednesday night will bring clear spells and further scattered showers, mainly in the north and west. Some of the showers will be wintry, especially in Ulster, though the showers will become increasingly isolated overnight. Lowest temperatures of -3C to +2C, coldest in the east and south, with a fairly widespread frost and some icy patches developing. Light to moderate north to northwest winds will be a little fresher near coasts.
Thursday
Cold and frosty to begin on Thursday with sunny spells. Showers, mainly in the west and north, some of them still wintry, will become increasingly isolated as the day goes on. Highest temperatures of 3C to 7C in light to moderate northwesterly breezes, still fresh at times near eastern and southern coasts.
Dry and turning very cold soon after dark on Thursday night, with clear skies and light variable breezes. Cloud will gradually thicken from the west overnight with patchy rain and drizzle developing near Atlantic coasts towards morning. Lowest temperatures of -3C to +2C with frost and icy patches.