Met Éireann has issued a number of rain alerts for southern counties, warning of the possibility of flooding and difficult travelling conditions.
A Status Orange rain warning has been issued for counties Cork and Waterford.
The warning will be in effect from 8pm tonight until 5am tomorrow morning.
Met Éireann is warning of heavy rain and possible thundery downpours.
The forecaster said this could lead to river flooding, especially in mountainous areas, and difficult travelling conditions throughout the county.
Meanwhile, a Status Yellow rain warning will be in place for counties Cork, Kerry and Waterford from 5pm this afternoon until 5am tomorrow morning.
A Status Yellow rain warning for Carlow, Kilkenny and Wexford will be in place from 8pm this evening until 8am tomorrow morning.
Met Éireann is warning of spells of heavy rain with the possibility of a few thundery downpours.
It said possible impacts include localised flooding and difficult travelling conditions.
A Status Yellow rain warning has been issued by the UK Met Office for counties Antrim, Armagh and Down from midnight tonight until noon tomorrow.