Met Eireann has issued a status yellow rainfall warning for this evening.
Thundery downpours are expected with an ongoing risk of flooding.
Dublin, Wicklow, Wexford and Waterford will be worst affected, with up to 30 millimetres of rain due to fall overnight.
Status yellow weather alert has been issued. Please see http://t.co/QtEBJI5qjm for details.— Met Éireann (@MetEireann) November 14, 2014
Motorists are being urged to reduce their speed, and avoid driving through deep floods.
Brian Farrell of the Road Safety Authority, said: "Motorists need to watch out for water run-off which can make for very slippery conditions on the roads and that is particularly the case on high-speed roads like motorways and dual carriageways.
"The really important thing to do there is to slow down, give yourself plenty of time and space to react in an emergency.
"The most important thing to do is not to try and drive through flooded roads because the water could be much deeper than you think."