Cork and Waterford have been issued with a status yellow rain warning, that is due to kick in later on Sunday evening.
Heavy and persistent rain will lead to spot flooding, Met Éireann says in the warning, which was issued on Saturday afternoon.
It is valid for Cork from 5pm until 11pm.
While for Waterford, the warning kicks in at 6pm and lasts until midnight on Monday.
Elsewhere, on Saturday, most areas will be dry from mid-afternoon with just well scattered showers following.
It will be generally dry and clear this evening, with Met Éireann saying things will feel "fresh"
Temperatures will hit a high of 13C on Saturday.
For the rest of the country, Sunday will begin largely dry with hazy sunny spells, according to the latest forecast.
However, cloud will gradually thicken with scattered outbreaks of rain and drizzle developing.
During the evening, persistent and heavy rain will affect southern counties with spot flooding.
Temperatures will reach highs of 7C to 10C in the northern half of the country, though slightly warmer in the south with highs of 14C.
A yellow weather warning is usually issued for weather that does not pose a threat to the general population but is potentially dangerous on a localised scale.
It is generally issued as a rain alert if between 30mm – 50mm in 24 hours is expected.
Check out the Irish Examiner's WEATHER CENTRE for regularly updated short and long range forecasts wherever you are.