Met Éireann has issued a Status Yellow rain warning for four counties.
Cork, Kerry, Waterford and Wexford can expect heavy thundery rain this weekend.
The warning is in place from 4:00a.m until 11:00a.m on Sunday (September 27).
Potential impacts include: localised flooding; poor visibility; and difficult travelling conditions.
In addition, the combination of spring tides, surge and strong onshore winds may result in wave overtopping along the Wexford coastline, Met Éireann said.
Met Éireann has updated its forecast for the weather this weekend.
Today (Friday) will be mostly cloudy for a time, but mainly dry, with just a few isolated showers around.
It will gradually brighten up from the west through the morning and afternoon with sunny spells developing.
During the evening, showers will become a little bit more frequent and heavier in some western and north-western parts.
Tonight will bring a mix of clear spells and showers, some heavy, with the showers mainly in the north and west.
Tomorrow will bring a mix of sunny spells and just well-scattered showers for a time.
It will become cloudier in the west and north through the afternoon and evening, with more frequent showers developing.
There will be clear spells to start Saturday night.
Cloud will build overnight with rain developing in western and southern areas, turning heavy at times and extending north-easterly.
It will be generally cloudy on Sunday with outbreaks of rain for many, possibly turning heavy in some places.
The rain will clear north-eastwards to scattered showers and sunny spells by the afternoon.