The first of two status yellow weather warnings for rain will kick in at 2 o'clock this afternoon.
Munster and seven other counties will see heavy rain with thundery downpours until 3am tomorrow.
The rest of the country will be affected from 5 o'clock this evening, with difficult travelling conditions.
Met Eireann Meteorologist, Liz Walsh says people need to keep an eye as it could be upgraded to Orange:
"Do have a at the moment have a yellow rainfall warning in operation but there is potential for this to be upgraded later this morning to orange for some locations. So the advice would be to stay tuned to the local forecast for your area and be prepared. Make sure that you clear those drains and gutters if you can and take care of your eyes on the road later today, as there is likely to be some spot flooding."