Met Éireann has issued a status yellow rain warning for eight counties from Tuesday.
For Cork and Kerry, the warning will come into effect at 12am and last until 2pm.
In Carlow, Kilkenny, Wexford, Wicklow, Tipperary and Waterford, the warning is set from 2am to 5pm.
Spells of heavy rain and possible flooding, difficult travel conditions and poor visibility are to be expected.
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The weather in Ireland on Monday evening will start off mainly dry, the forecaster said. Heavy and persistent rain will spread from the southwest overnight and spot flooding is possible. Lowest temperatures will range from 1 to 7 degrees.
Tuesday will be wet from the offset with spells of persistent and heavy rain in many areas and potential localised flooding.
In the evening, the rain will become confined to Ulster with only a few showers elsewhere. Highest temperatures will reach 11 to 14 degrees, with moderate to fresh south to southeast winds. Overnight, patches of mist and fog will develop.
On Wednesday, mist and fog will clear and brighter and sunnier spells will develop. In the afternoon, rain will begin in the south and spread northwards in the evening, becoming heavy at times. Rain will continue overnight but will be lighter. Highest temperatures will reach 11 to 13 degrees.
Thursday will be mostly cloudy with some showers of rain or drizzle. Highest temperatures will be from 8 to 13 degrees, with moderate to fresh northeasterly winds. Thursday night will see some patchy rain and will be mostly cloudy. Rain may become persistent in the south overnight.
On Friday, rain will spread northwards, although much of Ulster may stay mainly dry. The southern half of the country will see outbreaks of rain on Friday night. Highest temperatures will range from 7 to 11 degrees with fresh easterly winds.
