Met Éireann has issued a Yellow weather warning for rainfall in Cork tomorrow.
Up to 30mm will fall in places, with locally higher accumulations in upland and coastal areas, leading to spot flooding.
The warning will be in effect from 3pm tomorrow until noon on Wednesday.
The heavy rain will follow subzero temperatures forecast for tonight.
Met Éireann said clear skies across Munster will see temperatures fall to zero to -2 C. with a widespread hard frost and icy stretches on some roads.
Some patches of mist and fog are likely to form also in slack variable breezes.