The weather will become increasingly unsettled with rain or showers on most days over the coming week, according to Met Éireann.
It will be fresh at first, but will become warm and humid from Friday onwards again, the national meteorological office has said.
There is also a risk of conditions conducive to the spread of potato blight in western and northern coastal areas.
Drying will become poor to moderate with changeable conditions forecast; meanwhile, spraying conditions are also expected to deteriorate from today onward.
These deficits will reduce by at least 20mm over the coming seven-day period.
Today, Wednesday, July 17, will be cloudy with outbreaks of rain, which could be persistent or heavy at times, especially along the south coast and over the north.
It will be slightly cooler today than in recent days with top temperatures of 17° to 20° in moderate to fresh and gusty southerly winds, which will veer westerly and moderate as the rain clears.
The last of the rain will clear from the east this evening and tonight will become mostly dry with clear spells but scattered showers will affect the west and north.
Lowest temperatures will drop to 10° to 13° in a light to moderate westerly breeze.
Tomorrow will see scattered showers and sunny spells with the risk of heavy or prolonged showers in the north.
Showers will die out early tomorrow night with some clear spells.
However, a band of persistent rain will push in over Munster and west Connacht before dawn.
Lowest temperatures will drop to 10° to 13°. Moderate south-west winds will back southerly and drop off light.
The rain will spread countrywide early Friday morning, turning heavy in places.
Friday will be warm and humid, with top temperatures of 18° to 22°, according to Met Éireann.