After weeks of dry weather, there's a yellow warning for rain.
Areas including Dublin are being told up to 40 millimetres could fall between 9pm tonight and 9am tomorrow morning.
The warning covers Leinster, Cavan, Monaghan, Donegal and Waterford, and could see thundery downpours in places.
Liz Gavin, a forecaster with Met Eireann, says there will be "some heavy bands of rain pushing in from the West later on today and overnight as well".
Despite the rain forecast, Irish Water is going to continue to reduce overnight water pressure across Dublin.
The group has also confirmed that the national hose-pipe ban will also remain in place, to help rebuild supply after the heatwave.
It says the situation "will remain critical up to and possibly beyond mid-August".
The most severe conditions continue to be in the east and south, where the rivers, lakes and groundwater tables are at record lows.
According to Irish Water, data shows over half of rivers are at levels that were previously unheard of in July.
Kate Gannon from Irish Water admitted that the reductions can have a negative impact on homes and businesses, adding that the group is "continuing to monitor the situation very closely".
The Road Safety Authority is reminding drivers to watch out for flash flooding and the risk of aquaplaning.
Following the dry spell, it's warning a build-up of oil and rubber mixed with rainwater could create very slippy conditions for drivers.
The advice is to slow down and increase braking distance.