Status Yellow rain warnings have been issued by Met Éireann as heavy and persistent rain is expected from tonight (October 6).
For counties Donegal, Leitrim, Galway, Mayo and Sligo, a warning is in place from midnight until 3:00a.m on Saturday.
For Cork and Kerry, a rain warning is in place from midday on Thursday until 3:00a.m on Saturday.
As can be expected with rain warnings, prolonged rain with heavier bursts at times can be expected, and it will be heaviest and most persistent later on Friday.
Significant accumulations are possible in upland areas, and there is a risk of localised flooding.
On Tuesday, Met Éireann had issued a weather advisory for Connacht along with counties Clare, Cork, Kerry, Limerick and Donegal.
The national forecaster warned that a band of rain was approaching from the Atlantic and is forecast to stall over the western half of the country on Thursday and Friday, leading to persistent and heavy falls in places.
Nationally, Met Éireann said that outbreaks of rain will continue until early Saturday. High pressure moves in over the weekend, remaining in situ through much of next week as well bringing mostly settled weather.
Tonight is going to be misty and murky, with scattered outbreaks of rain and drizzle. The rain and drizzle will be most persistent in the west and south, remaining mostly dry further east.