Met Eireann has issued a nationwide warning for heavy rain that could last up to three days.
While the alert is only in place from Monday until Tuesday night, the national forecaster said that the showers will begin on Sunday evening.
The caution states that both spot and flash flooding are possible as the country gets drenched.
The warning says: "Persistent and occasionally heavy bands of rain will cross the country beginning on Sunday night through to Tuesday evening.
"While some areas will remain below warning levels, there is a risk of localized spot flooding with a heightened risk of flash flooding in mountainous regions where accumulations are expected to be highest.
"This warning will be reviewed and may be elevated in further updates to reflect the evolving situation."
Earlier, Met Eireann had explained that as the weekend ends, the whole country will suffer from a "period of unsettled weather", with heavy rain and flooding both set to hit.
A spokesman said: "Conditions turning unsettled by the end of the weekend, with a spell of very wet and at times windy weather on Monday and Tuesday.
"Persistent and locally heavy rainfall, coupled with high soil saturation levels, brings a risk of river and surface flooding.
"Unusually high tides combined with strong winds gives an elevated risk of coastal flooding. Warnings will be issued on Sunday."
