Up to 8cm of snow forecast over next two days
A status orange weather warning has been issued for counties Cavan, Monaghan, Donegal, Longford, Leitrim, Mayo and Sligo.
Snow showers are forecast to occur on Thursday evening, Thursday night and during Friday.
Met Éireann is expecting accumulations of 4cm to 8cm (up to 3in), with the larger values on high ground. Icy roads and footpaths will also be a factor, it said.
The warning is valid from 4pm on Thursday until 6pm on Friday.
Yellow warning extended
Meanwhile, Met Éireann has extended its status yellow snow-ice warning to all of Munster.
Dublin, Carlow, Kildare, Kilkenny, Laois, Louth, Wexford, Wicklow, Offaly, Westmeath, Meath and Roscommon have also all been included in the warning.
Occasional snow showers will occur on Thursday evening, night and during Friday, with accumulations of up to 3cm (just over 1in) expected.
Some icy roads and footpaths are also forecast.
The warning is in place from 4pm on Thursday until 6pm on Friday.