Met Éireann has issued a Status Yellow rain warning for nine counties as heavy showers are forecast overnight.
The warning for Clare, Kerry, Donegal, Galway, Leitrim, Mayo and Sligo came into effect at 10pm and will end at 7am tomorrow morning.
The warning for Cork and Waterford came into effect at 10pm and will end at 11am tomorrow morning.
The forecaster said outdoor events may be impacted, along with a risk of localised flooding and difficult travelling conditions.
Rain will be heavy and persistent at times, with potential localised flooding due to saturated ground conditions, according to the forecaster.
Met Éireann and gardaí have both warned of difficult driving conditions.
"We're asking you to plan your journey, paying attention to local conditions, slow down and be mindful of others on the roads," gardaí said.
