Met Éireann has issued a yellow rain warning for Kerry, Cork, Limerick, Clare and Galway that is set to last until midday on Monday.
There is set to be a risk of localised flooding, with the warning coming into effect after 10:30am on Sunday morning.
The forecaster said there will be poor visibility as a result, with difficult travelling conditions for the affected areas.
Rain will extend to remaining areas and will continue overnight, heavy at times, especially in the west and south west with the likelihood of localised flooding.
The highest temperatures nationwide will be between seven and 11 degrees, with light to moderate westerly winds.
Monday morning will be mostly cloudy with further rain, which will continue for much of the day in the east and north, but will give way to showers and a few bright spells.
