Met Éireann has issued a weather advisory for 15 counties today.
The advisory is in place for all of Connacht, Longford, Offaly, Westmeath, Cavan, Donegal, Clare, Cork, Kerry, Limerick and Tipperary.
The forecaster warned: "Periods of heavy rainfall from Saturday to Tuesday may lead to some local flooding as river levels remain elevated.
"The heaviest of the rain will be through Saturday afternoon, and again early Monday and early Tuesday, with rainfall accumulations from Saturday to Tuesday of 40 to 50mm in places, with some spot flooding.
"Strong winds at times also, with gales on coasts."
The advisory is valid from midday on Saturday until 6pm on Tuesday.
Met Éireann said that Saturday will "be a mostly cloudy and blustery day".
They said eastern areas will "will see a good deal of dry weather up until early afternoon" when the "odd patch" of light rain will emerge.
In the west, they are predicting that "patchy rain and drizzle will turn persistent, and occasionally heavy by afternoon".
They added: "The rain in western areas will extend to all areas in the late afternoon and early evening with some heavy bursts possible, leading to some localised spot flooding."
Part of Saturday night will see widespread rain but "a transition to clear spells and showers" is expected to extend from the west.
Sunday will see a mix of sunny spells and scattered blustery showers.
Met Éireann is predicting that some of the showers "will be heavy with hail" and there is a "risk of isolated thunderstorms".
There are showers due on Sunday night, confined to the west and north, and the forecaster adds that "cloud will increase and rain will push in from the Atlantic overnight".