A status yellow rain warning has been issued for Cork with up to 40mm of rain expected to fall tomorrow night.
Met Éireann issued the warning for all of Munster and Leinster and it will be in effect from 7pm Thursday evening until 7am Friday morning.
"Accumulations of 25 to 40mm will occur over a relatively short time period. Spot flooding is likely," Met Éireann has warned.
Tomorrow is expected to be a mainly dry day with just a few isolated showers amid sunny spells, but in the evening, after 7pm, the weather is to turn with the day becoming cloudy and rainy with thundery downpours.
Easterly winds are expected to increase to strong and gusty and temperatures will be around 13 to 15 degrees.
Friday morning, the heavy rain will clear from the north, Met Éireann said with showers easing on Friday night but scattered showers will continue along the coastal counties.
"Light to moderate westerly winds will increase fresh to strong by morning with lowest temperatures remaining around 13 to 15 degrees."
Saturday will be windy with isolated scattered showers and sunny spells. Top temperatures will be between 17 to 20 degrees and westerly winds will be fresh to strong and gusty but moderate later in the evening.
Later in the evening, showers will die out but may linger in the north and along Atlantic coastal counties. Lowest temperatures of 9 to 12 degrees in moderate westerly breezes easing later.
Sunday will be a mostly dry day but again, there will be some sunny spells and isolated showers, with a few turning heavy.