Hail and thunderstorms are also on the cards.
Met Éireann has issued a Status Yellow rain warning for Donegal valid from 3pm on Friday until the same time on Saturday.
The weather forecaster has said there will be heavy rain at times in the county over the 24 hours, bringing the potential for surface and river flooding.
For the rest of the country, Met Éireann says it will be windy at first on Friday evening, with bands of rain clearing to scattered showers overnight and turning wintry at times on higher ground.
There is also risk of hail and isolated thunderstorms as temperatures plummet to between 0 and 3 degrees.
It will continue to be cool and breezy over the weekend as blustery showers persist.
However, the weather will take a turn for the better as we enter next week, becoming more settled with drier, milder spring-like conditions expected.
This will be just in time for
St Patrick's Day next Wednesday with Met Éireann's current indications suggesting it will remain dry with highest temperatures ranging from 11 to 16 degrees.
