Donegal, Mayo and Sligo will be on yellow alert for persistent rainfall – with falls of up to 50mm expected from tonight.
It follows a weather warning by Met Eireann for the three counties for early this week – amid fears another storm could hit Ireland before the weekend.
Weather chiefs have warned there’s a risk of spot flooding for the areas.
The warning kicks in this evening at 6pm and will remain in place for 24 hours.
A Met Eireann forecaster said: “A slow moving band of rain is expected to bring heavy and persistent rain over the period with rainfall amounts of 25-50mm expected.
“There is potential for higher amounts in mountainous regions. Spot flooding possible.”
The north west will see up to 50mm accumulations of rain early in the week
They added: “Further rainfall is expected to follow Monday night and Tuesday.”