It was a free-for-all in Dublin last night with suspended bus lanes and free access to toll bridges after flooding caused traffic mayhem.
Counties along the east coast and parts of the midlands also experienced serious flooding, and there is a continued risk of more disruption today due to further rainfall.
The highest rainfall was in Dublin, with more than 60 millimetres recorded over 16 hours. In an unusual statement the Garda said it wished to notify the public "that bus lanes have been suspended due to weather conditions. In effect, this means that it is a free-for-all. Go for it".
Dublin's north side was worst affected, with many homes flooded, particularly in the Glasnevin area. The river Tolka burst its banks and the north quays were closed.
Motorists are advised to add an hour to their journey time to Dublin Airport due to flooding on the M50 and on other access roads.
Met Éireann said that it would be overcast this morning with further outbreaks of rain and local floods. Rain will be persistent over eastern counties but it will brighten later from the west.
Callers to The Irish Times said it took them up to five hours to travel from the city centre by car last night to suburbs on the north side of Dublin and to parts of Co Meath.