Warnings of spot flooding have also been issued.
Met Éireann has issued Status Yellow rainfall warnings for six counties.
The national forecaster says spot flooding is possible for Donegal, Galway and Mayo between now and lunchtime tomorrow.
''Heavy rain with additional accumulations of 20 to 40mm expected'', a forecaster wrote.
''Spot flooding possible, with poor visibility and poor driving conditions''.
Valid: 09:00 Tuesday 04/08/2020 to 13:00 Wednesday 05/08/2020
Weather Alert
Level: YellowRainfall warning for Clare, Cork and Kerry
Valid from 15:00 Tue, 04-Aug-2020
Valid until 12:00 Wed, 05-Aug-2020 pic.twitter.com/zloPuMnHKN— Met Éireann (@MetEireann) August 4, 2020
While an alert for Clare, Cork and Kerry will kick in at 3pm this afternoon and is valid until midday tomorrow.
''Heavy rain this evening, tonight and tomorrow morning will give accumulations of 20 to 40mm, with potentially higher amounts in mountainous areas. As soils are saturated from recent rainfall this additional rainfall will lead to spot flooding''.