A Status Yellow rainfall warning is in place for Connacht, Longford, Donegal, Clare and Kerry.
Met Éireann said heavy rainfall is expected through the day Wednesday and into Wednesday night, with 25 to 40mm expected.
The forecaster said localised flooding is likely as ground is saturated at the moment and river levels are elevated following recent heavy rainfall.
The warning is expected to remain in place until 4am tomorrow.
TODAY
Wet and rather windy today with widespread rain, heavy at times in west Munster, Connacht and west Ulster, with a risk of flooding.
There will be some occasional drier spells too, with the best of these across the east and southeast.
It should feel somewhat milder than recent days though, with highest temperatures of 9C or 10C in fresh to strong and gusty southwest winds, strongest along Atlantic coasts.
TONIGHT
Further falls of rain into tonight, heaviest across Atlantic counties early on, and later across the east and southeast.
Misty too, as southwest to west winds ease.
A cold night, with lows of 1C to 4C. Some frost and ice is possible in the clearance from the northwest later.
Information supplied by Met Éireann
