Thundery downpours are also possible along with localised spot flooding.
A status yellow rainfall warning for tomorrow has been issued for 14 counties including Laois and Offaly.
Met Eireann says heavy rain overnight and into tomorrow morning could lead to accumulations of 25 to 40 millimetres in places.
Thundery downpours are also possible along with localised spot flooding.
The warning comes into effect from 2am tomorrow morning, and will stay in place until just before midnight.