Counties Galway, Mayo, Clare, Cork and Kerry have been issued a Status Yellow rainfall warning by Met Éireann.
The warning will come into effect from 6pm today until 6pm on Wednesday which will bring 30 to 50mm of rain in certain parts of the country.
Mountainous regions will potentially receive higher volumes of rainfall and there will be a high possibility of flooding.
However, countrywide rainfall is to be expected tonight.