Met Eireann forecasters have issued a status yellow weather warning for three counties.
The snow-ice caution, put into place for Cavan, Monaghan and Donegal, will begin at 11pm tonight and last until 8am tomorrow morning.
Forecasters warn that a band of heavy rain will move up from the south on Saturday night.
The rain will turn to sleet and snow in some places as it begins to encounter the cold air - with some temporary accumulations possible.
There will also be snowfall in the highest upland parts of Donegal.
But, in bad news for anyone hoping for a snowy weekend, the snow will turn back to rain alter on Sunday morning after mild air moves up from the south.
It comes as Met Eireann forecasters warned that temperatures were set to plummet this weekend - and some sleet setting in.
On Saturday's weather conditions, they said:
"Cloudy and misty in most areas this morning with outbreaks of rain and drizzle. Falls of sleet or wet snow are possible for a time in Ulster and north Leinster, but mainly over high ground.
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"The rain will turn light and patchy this afternoon with good dry periods developing. Milder air will extend to Munster with afternoon highs of 10 or 11 degrees.
"However, colder elsewhere with maximum temperatures of just 1 to 5 degrees. Fresh westerly breezes in the south but winds will be light and variable elsewhere."
There will also be snowfall in the highest upland parts of Donegal.
But, in bad news for anyone hoping for a snowy weekend, the snow will turn back to rain alter on Sunday morning after mild air moves up from the south.
It comes as Met Eireann forecasters warned that temperatures were set to plummet this weekend - and some sleet setting in.
On Saturday's weather conditions, they said:
