The status yellow warning was issued today and covers the entire country from 4pm on Thursday until 4pm on Friday.
According to Met Eireann there will be wintry showers right across the country with accumulations of snow over northern areas.
"There will be cold, wintry showers and probably show showers at night", he told the Donegal Democrat.
The wet weather today (Thursday) has been accompanied by temperatures reaching 12°C, but from tomorrow (Friday, December 8) it will feel much sharper with a maximum temperature of 3°C. High-sided vehicles and motorcyclists are particularly vulnerable to strong winds.
Forecasters say we're in for bitterly cold conditions until Sunday.
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Northwest winds will increase strong and gusty.
Donegal is among the counties in the north west that will be worst affected, with up to 3 centimetres of snow expected in places.
Meanwhile, the Road Safety Authority has warned motorists to expect the unexpected with high winds and icy conditions.
The Met Office has warned of flying debris that could lead to injuries or danger to life, while damage to property is also possible.