ESB crews are working on restoring power as up to 140,000 homes and businesses are without power.
Fallen trees on overhead lines are the main issue following high winds.
Most of the outages are along the west coast with some in Dublin.
The worst impacted areas are Cavan, Sligo, Galway, Thurles, Castlebar, Tralee, Portlaoise, Mullingar and Dundalk.
11am update : ESB Networks crews are working to restore power to 140,000 impacted by Storm Ali latest info here : https://t.co/O5GIQWfY5D— ESB Networks (@ESBNetworks) September 19, 2018
Please report any damage to electricity infrastructure immediately by calling 1850 372 999 pic.twitter.com/YEECJmKSmd
The second day of the National Ploughing Championships has been delayed further due to Storm Ali.
It was due to open around 11am but organisers are still meeting to assess the situation.
A final call on whether the event will go ahead today will be made at midday.
It is only the second time in its 87-year history that the farming festival has been delayed because of extreme weather.
Due to Storm Ali, there are line closures in on the following routes.— Iarnród Éireann (@IrishRail) September 19, 2018
Dundalk - Drogheda
Carrick on Shannon - Boyle
Clara - Tullamore
Crews are on route to clear lines, expect delays. Update to follow.
High winds due to #StormAli will have an impact on the flight schedule today. Some flights already cancelled. Please check with your airline before coming to the airport. Departures info here https://t.co/2bD7lEWGaJ. Arrivals info here https://t.co/ckiUMjBwFf. pic.twitter.com/bPgNBTFqAv— Dublin Airport (@DublinAirport) September 19, 2018