Met Éireann has issued a Status Yellow rain warning for counties Galway, Mayo and Kerry.
From 1:00a.m on Friday (August 20) until 4:00p.m, heavy and possibly thundery falls of rain at times can be expected, with a risk of localised flooding, the national forecaster said.
National forecast
Meanwhile, following a mainly cloudy and misty morning, today (Thursday) the weather will be mostly dry, with some bright or sunny spells developing.
However, patchy drizzle may persist in places. More persistent rain will develop in the southwest this evening.
Tonight, rain will extend from the Atlantic, turning heavy in parts of west Munster and west Connacht, but it will be patchy in the eastern half of the country and some eastern coastal areas will remain dry.
Tomorrow, nationally, will be cloudy and wet, with outbreaks of rain in all areas, heavy and possibly thundery in parts of west Munster, west Connacht and later in west Ulster, but eastern areas may have some dry spells.
Tomorrow evening, drier conditions will develop in west and southwest coastal counties and winds will fall light, mainly southwesterly. However, it will remain breezy and wet elsewhere, with rain turning heavier in the east.
It will become warmer over the weekend and next week.