Met Éireann issued a status yellow rain warning for counties Cork, Kerry, Limerick, Clare and Galway on Sunday morning.
The warning came into affect after 10.30am, and will run until 12pm on Monday.
With heavy rain expected throughout the day and into Sunday evening, the forecaster has warned of the potential for localised flooding, poor visibility and difficult travelling conditions in the affected counties.
Met Éireann is forecasting rain and drizzle for the southwest of the country on Sunday morning, with showers expected to “spread slowly north-eastward through the day”.
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Elsewhere in the country, northeast Leinster and Ulster will likely remain dry until after dark.
Highest temperatures nationwide will straddle between 7 and 11 degrees, with light to moderate westerly winds “becoming southerly and freshening”.
Outbreaks of rain will become heavier in the west and southwest later tonight, “with the likelihood of some localised flooding”, the forecaster said. Patches of mist and fog are also possible.
Temperatures will remain between 4 and 6 degrees in the south and southwest, but may reach 8 degrees elsewhere.
Into Monday morning, the rain will persist, and continue for much of the day as the weather pattern moves through the country. Heavier showers throughout the country come with a risk of some spot flooding, the forecaster said.
Showers are expected to give way in the evening, with the chance of “a few bright spells” in the west and south.
Temperatures on Monday will vary between 7 and 10 degrees, with light to moderate winds.
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