ESB Networks repair crews are battling to reconnect thousands of homes left without power after violent lightning storms.
Around 10,000 homes are still without power nationwide.
Motorists in Dublin were warned to exercise extreme caution due to heavy rainfall and the possibility of flooding on some roads.
The heavy rainfall has also resulted in water levels rising in the River Liffey.
However, the capital escaped one of the worst lightning storms of recent years with the bulk of the power outages and damage being inflicted on Cork, Waterford, Kilkenny and Wexford.
Homes were struck by lightning in Mullinavat in Kilkenny and Mayfield in Cork.
Karen Condon said her family cannot believe the damage caused to her mother's home at Avonmore Park in Cork after a lightning strike.
"My mother was in the house and we don't know if the bolt struck the chimney pot or the TV aerial," she said.
"But it blew a hole in the roof straight through the tiles and the heavy rainfall then started to pour in to the upstairs bedroom."
The semi-detached house suffered water damage to its upstairs rooms because of the shattered roof - while two other adjacent houses were also damaged by the lightning bolt.
At the height of the storm, over 20,000 homes and businesses were left without power.
ESB Networks official Mike Fitzgerald said repair crews were working to get everyone reconnected as soon as possible.
Over 10,000 customers had their power supplies restored overnight, while the ESB hopes the rest will have electricity switched back on by this afternoon.
The heaviest rainfall fell overnight in Cork and Kerry. Met Eireann said up to 50mm of rain was expected in a 24-hour period with the worst hitting the south west.
However, heavy rainfall was also predicted overnight for Waterford, Wexford and south Kilkenny.
Up to 40mm was expected to fall in parts of the south-east.
Galway City Council also said that a flood alert remains in place given the combined threat posed by rainfall on the River Corrib and high tides.
A tidal flood alert remains in place for Cork city after minor flooding at high tides at both 6am and 6pm yesterday.
However, the flooding was restricted to low-lying areas of Morrisson's Quay, Sharman-Crawford Street and Wandesford Quay.