MIAMI — The remnants of once-fearsome Hurricane Irma rolled through the southeast on Tuesday, still carrying flood risks and leaving a staggering recovery effort in its wake that includes simply trying to turn the lights back on across huge swaths of Florida.
The unprecedented outages — more than 54 percent of Florida customers were without power as of early Tuesday — also unleashed a cascade effect across the region. Millions of people who fled Irma may not be able to return home for weeks as crews struggle with downed lines and a storm-swamped electrical grid. And for those with a generator, fuel supplies depend on the success of a logistical network trying to keep gas flowing to all points of battered and sweltering Florida.
Florida was not alone. Blackouts hit more tens of thousands of homes and businesses in Georgia and South Carolina — with more blows possible as the remains of Irma move north from outside Atlanta. Some air service was scheduled to resume to Miami and other Florida airports, but hundreds of flights remained canceled in Atlanta, one of the country’s busiest transit hubs.
The National Hurricane Center said Irma, now classified as a post-tropical cyclone, was expected to weaken throughout Tuesday, but “localized intense rainfall” kept flood warnings in place from Alabama to South Carolina.
In Florida, the eye-popping numbers on the blackout did not tell the full story. Emergency officials said more than 5.6 million customer accounts were without power — down from a peak of about 6.5 million on Monday. But each account often represents more than one person, pushing the raw figures at one point to near 12 million, or more than half the state’s population.
Eric Silagy, president and chief executive of Florida Power and Light, the state’s largest utility, said Monday as many as 9 million people were affected by his company’s outages alone. Shawna Berger, a spokeswoman for Duke Energy, said 1.2 million of its 1.8 million customers were without power Monday in Florida and noted that if you multiply that number by 2.5 — per the latest census data, she said — that shows that 3 million people were affected at the peak blackouts.
“We’ve never had that many outages,” Silagy said. “I don’t think any utility in the country has.”
Remarkably, it could have been much worse.
That was the grateful mantra on the lips of many on Monday. Though there was significant property damage in the Florida Keys and in some parts of southwest Florida, officials said there were investigating just a small number of fatalities that came as the storm made landfall. It was unclear how many were directly related to the storm.
Damage to water supplies in the Keys remained a top concern, however. A Defense Department statement said an estimated 10,000 people who rode out the hurricane in the Keys could still face evacuation. But there were no immediate plans underway to move people from the island chain.
Waters in Jacksonville, in the state’s far northeast, sent residents scrambling to the top floors of their houses. The St. Johns River, which cuts through the city, overflowed its banks, flooding bridges and streets.
Rescuers used boats, water scooters and even surfboards to get to residents surprised by the rising waters, said Kimberly Morgan, a spokeswoman for the Clay County emergency center. “You have to get creative in a situation like this,” she said.
“We don’t think we’re going to see the end of this until Friday,” she said.
Gov. Rick Scott (R) called the flooding in Jacksonville “historic” — officials said the city could end up with four feet of standing water — and he warned the many residents still stuck in the dark that “it’s going to take us a long time to get the power back up.”
Marilyn Miller awoke in St. Petersburg at 1:30 a.m. Monday to a pitch-black house. A native Floridian, Miller was expecting the outages and has even gotten used to them after enduring years of tropical storms.
What she didn’t expect, she said, was the possibility that the blackout could last for days.
As neighbor after neighbor on her block tried to call Duke Energy for help, they heard that just 80 homes in their neighborhood had lost power — out of more than 100,000 across Pinellas County.
It became clear, Miller said, that her neighborhood would not be the priority. So she started making readjustments to a time before technology.
“I need my cellphone. It wakes me up in the morning for work. I need my air conditioner at nighttime,” she said. “Can’t cook. Can’t see. Can’t do anything.”
Driving in many cities remained extremely hazardous — an exercise in vigilance due to downed trees and the ubiquitous palm fronds that lurked in wait like alligators on the street. In Miami, some residents expressed frustration about the evacuations, which in many cases ultimately weren’t necessary.
“Everyone got stirred up, and they were told to leave,” said Sara Edelman, 29, a biologist walking along 104th Street with her mother, Philis Edelman, 60, an officer worker. “And now there’s no one to clean the trees up.”
Dan Zumpano, 44, who lives nearby, said he believes authorities began evacuations “way too early” in an abundance of caution, driving people from places that ultimately weren’t seriously impacted by the storm into areas that were: “I thought it was the right thing to do, but I think they sent a lot of people right into the core of the hurricane.”
That was a familiar story: People who evacuated from Miami to Tampa. And then, in some cases, from Tampa to Orlando. The storm followed many of them the entire time. “Every day you saw the models changing,” Zumpano said.
But all along Miami’s streets, signs also remained of the hurricane’s fury and the tragic possibilities that might have been.
Sailboats on Miami’s Coconut Grove marina were flipped over. Million-dollar yachts were half submerged in the bay. Once-idyllic parks looked like desolate war zones. Large trees toppled over, roots dangling in the air.
Resident Paul Plante came to the marina to check on his home and boat, which he had docked indoors. His boat was fine, and he and his sister looked in disbelief at the submerged boats in the bay that weren’t so lucky.
“You have to take nine different roads to get here now, but everything was okay,” he said. “The storm surge could have been so much worse. We’re lucky.”
Berman reported from Washington. Brian Murphy, Katie Zezima, William Wan, Angela Fritz and Sandhya Somashekar in Washington, Darryl Fears in Orlando, Perry Stein in Miami, Patricia Sullivan in Estero, Fla., Lori Rozsa in Gainesville, Dustin Waters in Charleston, S.C., and Scott Unger in Key West, Fla., contributed to this report.