Motorists were warned tonight to take extra care over the weekend as temperatures are forecast to plummet to -5C.
The Road Safety Authority (RSA) said heavy rain will fall in parts of the north, Connacht and east followed by freezing temperatures and morning fog.
It is feared this combination will lead to icy driving conditions and reduced visibility.
The RSA told motorists to drive slowly, allow extra room between cars and to manoeuvre gently.
Cyclists, pedestrians and motorcyclists were also advised to wear high-visibility clothing or carry a torch in fog or darkness.
The guide, Severe Weather Advice For Road Users, is available on the RSA website.
Met Éireann said there will also be overnight frost and fog on Saturday night with temperatures rising to between 4C and 7C on Sunday.