The northern half of the country can expect scattered showers in the morning, while outbreaks of rain or drizzle will sweep across the southwest in the afternoon.
Met Éireann predicts top temperatures of 17C to 22C, with moderate westerly winds.
This evening will stay mild and humid, but there will be heavy, persistent rain throughout the night and into tomorrow morning.
After a wet start to Saturday morning, the rain should clear to light showers in the afternoon.
It will be a mild evening with temperatures climbing to 22C, and a fresh south to southwest wind should offer some relief from the humidity.
Temperatures will fall to 13C on Saturday night, with scattered showers continuing in the west and north, while eastern parts of the country enjoy clear spells.
The showers will return on Sunday, becoming widespread and heavy throughout the day. Areas in the west and north can expect long spells of rainfall.
Forecasters predict another mild and humid week from Monday, with a mix of scattered showers and good sunny spells over the first half of the week.