Met Éireann has issued a status yellow weather warning for Galway and eight other counties.
The warning for heavy rain will start at midnight on Monday, and will remain in place overnight and throughout Tuesday.
Rainfall of 30 to 50mm is expected which may lead to some surface flooding, and Met Éireann says the heavy rain will further elevate river levels which could lead to river flooding.
The warning covers Connacht, Donegal, Cork, Kerry and Waterford.
A separate wind warning has been issued for Munster and Wexford but this does not extend as far as Galway.
Before the miserable weather on Tuesday, though, we will get some dry and decent weather.
Tomorrow (Monday) will be mostly dry and bright, winds will will be mostly light and afternoon temperatures will reach 18 to 20 degrees.
