A status yellow rain warning has been issued for Donegal and ten other counties tonight and tomorrow morning.
Met Eireann is warning of local flooding risks as heavy and persistent rain sets in from 4pm this afternoon.
Intense rainfall with totals of 25 to 40mm can be expected at times.
Rainfall levels will be highest amounts in the southwest of the country and in mountainous areas, according to Met Eireann.
The warning is valid from 4pm today (Tuesday) until midday tomorrow, Wednesday.
The rain is forecast to clear through the morning and scattered showers will follow in behind. Tomorrow will see brighter conditions with some sunny spells.
“Turning cooler and more unsettled for the rest of the week and weekend,” said Met Eireann’s National Outlook.