A snow and ice warning for Connacht and Cavan and Donegal comes into force at 6pm on Sunday.
Met Éireann said the status yellow warning, the lowest of the three warning categories, see hail, sleet and snow showers with accumulations of snow on high ground.
The warning will remain in place until 11am on Monday.
Met Éireann meteorologist Liz Coleman said temperatures would fall sharply on Sunday evening to below freezing.
“On Sunday night, there will be a more organised band of showers coming in across country, and with that a higher risk of some wintry precipitation,” she said.
“In terms of blankets of snow - no,” said Ms Coleman.
“We don’t expect that. Showers might fall as sleet or snow on higher ground.”
The pattern is set to continue into Monday and Tuesday - with scattered showers, some wintry forecast - before a band of rain coming from the south west on Wednesday is expected to increase temperatures.