As much as eight centimetres of snow could fall on low ground in Donegal on Thursday and Friday.
Met Éireann issued the orange status weather warning of snow and ice shortly after 4pm on Thursday.
The warning is valid from 4:00p.m. on Thursday through to 6:00pm on Friday.
"Snow showers will occur this evening [Thursday], tonight and during Friday," read the warning on the official Met Éireann website.
"Accumulations of four to eight centimetres are expected, with the larger values on high ground. Icy roads and footpaths."
Met Éireann's weather warning applies to counties Cavan, Monaghan, Donegal, Longford, Leitrim, Mayo and Sligo.
UK counterpart, the Met Office, issued a yellow status weather warning for snow and ice across the North of Ireland.
The Met Office warning is valid from Friday through to Sunday.