Spokesman Rob Gould said Sunday that an estimated 3.4 million homes and businesses will lose power once the worst of Irma reaches the Florida mainland.
Florida Power & Light announced on Thursday it will shut down the Turkey Point and St. Lucie nuclear plants ahead of Irma's expected arrival this weekend.
As of 9 a.m.in Miami-Dade, 574,490 customers didn't have power out of a total 1.1 million customers, according to FPL's data. More than 76,000 people in the state are already without power, according to Gov. Rick Scott.
Stay far away from downed power lines and anything that may be in contact with a downed power line. It could become a Category 5 at any time. "After the storm hits, our crews will begin working to restore power as soon as conditions are safe", the company said in a statement.
FPL also said it will proactively shut down certain substations before they flood, so they can turn them back online more quickly.
The enormous storm covers an area more than double the size of the state, and on Sunday had maximum sustained winds of 130 miles an hour.
The electric utility can see whether a house or business is out of power even in the field via iPads, which utility restoration workers will be using in their work.
48 hours after landfall, county by county estimates are given and finally 96 hours after landfall they provide restoration estimate at a more local level.