The Minister with responsibility for flooding says communities along the Shannon particularly need to be on alert over the next 48 hours.
A Status Yellow Warning for heavy rain's in place until 9pm tonight across Connacht, the midlands and north-west.
Met Eireann says up to 50 millimetres of rain could fall in places, and there's a risk of some rivers overflowing.
Minister of State, Patrick O'Donovan, says homes and businesses along the Shannon need to be especially wary: