A status yellow rain warning is currently in place for Cork, Galway, Kerry and Mayo.
Met Éireann said there will heavy rain at times on Thursday which may cause localised flooding.
Rain accompanied by fresh to strong winds will lead to poor travelling conditions. Rainfall totals will be higher in mountainous regions.
The warning is valid from 10am on Thursday to 8pm this evening.
Overall, Thursday will see a freshening southerly wind which will bring rain and drizzle eastwards through this morning, becoming widespread in the afternoon.
Heaviest and most persistent rain across Atlantic counties with spot flooding possible. Highest temperatures of 15 to 19 degrees as southerly winds become fresh to strong.
Friday will see scattered heavy showers with isolated thunderstorms mainly over the western half of the country in the morning, it will be drier with sunny spells in the east.
Warm and humid, especially in any sunshine with highest temperatures of 18 to 23 degrees, it will be warmest in the north this weekend, in mostly fresh southeast winds.
On Saturday thundery rain will move northwards across the country. Sunshine and moderating westerly breezes will later follow. Highest temperatures of 18 to 23 degrees.
After a dry start Sunday afternoon showers will be widespread and heavy with possible spot flooding. Highest temperatures 17 to 21 degrees, in light to moderate southerly breezes.
It is a similar story on Monday with sunshine and frequent showers, some of them heavy in the afternoon. Highest temperatures 17 to 20 degrees in light variable breezes.
The picture remains unsettled in to the extended outlook period.
