A status yellow rainfall warning has been issued for Cork, Kerry and Waterford.
The warning comes into effect at 11am tomorrow, Saturday, June 20 and will remain in place for a twelve-hour period until 11pm that night.
"Spells of heavy rain with amounts of 25 to 35mm and spot flooding.
"Reduced visibility and hazardous driving conditions," Met Éireann states.
Tomorrow patchy rain and drizzle will develop during the morning with heavier downpours expected in the afternoon.
The national forecaster has warned that there is a risk of some spot flooding.
"Rain will turn persistent and heavy in places during the afternoon in a strengthening southeasterly wind.
"There is potential for spot flooding," Met Éireann states.
Winds in coastal areas could be "strong to near gale".
However, these winds are expected to veer southwest and ease somewhat moving into tomorrow evening.
Maximum temperatures will be between 14 and 17 degrees.
Sunday will bring a mix of cloud, sunshine and passing showers.
Cork could escape the worst of the downpours as Met Éireann has stated that showers will be "most frequent in the north and west".
Maximum temperatures on Sunday will be between 14 and 18 degrees, coolest in the west, in moderate to fresh southwesterly winds.
On Sunday night, Met Éireann states that "southerly winds will fall light for a time before backing southeast and increasing moderate to fresh and gusty by dawn".
Early indications for next week show that this "unsettled theme" looks likely to continue.