The River Lee has burst its banks along the south channel in Cork City.
Gardaí say traffic diversions are in place in the area.
There is flooding on Wandesford Quay, Morrison's Island, South Terrace, Union Quay and Father Matthew Quay.
Motorists are being advised to use alternative routes.
CORK: High tide affecting some routes around Cork City again this eve. Flooding on Wandesford Quay, Morrison's Island, South Terrace [1/2]
— The AA Ireland (@aaroadwatch) October 28, 2015
CORK: ... Union Quay and Father Matthew Quay. Motorists should use alternative routes. [2/2]
— The AA Ireland (@aaroadwatch) October 28, 2015