Post-tropical cyclone Isaias pushed deeper into the US Southeast on Thursday, carrying the risk of flash flooding and powerful gusts well beyond the coast as it tracked across southern Alabama, the National Hurricane Center said.
The system was centered about 88.5km south-southwest of Montgomery, Alabama, with maximum sustained winds of 100km/h, the agency reported.
Forecasters expect Isaias to keep weakening, but warned it would still whip up gusty winds far inland before dropping below gale force later, according to the NHC.
Before losing strength, Isaias slammed into the US Gulf Coast with heavy rain and damaging winds as it came ashore in northwestern Florida, the center said.
“Isaias makes landfall near Destin, Florida,” the NHC said in an earlier update.
“Life threatening storm surge impacting Gulf Coast as dangerous hurricane conditions and flash flooding spread inland,” it said, shortly before the storm was downgraded to a post-tropical cyclone.
After making landfall near Destin, Isaias shed wind speed quickly — first weakening into a Category One event and then dropping further to a post-tropical cyclone, the NHC said. Even as it unraveled, officials cautioned that storm surge and flooding remained dangerous, with power connections snapping in places.
Florida emergency services urged people to shelter in place and stay alert for hurricane conditions across the state’s north, after Isaias initially reached land as a Category Two storm.
Along the coast, mandatory evacuations were ordered in some communities and businesses boarded up or closed as Isaias became the first hurricane of an Atlantic season that began in June — a season largely tempered so far by a historic El Niño pattern that typically shifts stronger storm development toward the Pacific.
In Pensacola, about 80 kilometres west of Destin, winds tore roofing from some homes and businesses, snapped tree limbs and knocked out electricity, residents and reporters said.
Debris on an intersection as wind and rain from Hurricane Isaias pass through Pensacola in Florida
“Things are flying really fast and I’ve never seen wind this fast before, so it’s intense, it’s scary,” Jonathan Ramos, a 40-year-old government employee, said at his hotel in Pensacola, where the power went out.
“I don’t recommend people coming down here for fun to do this,” he added.
As the storm hit shore, nearly 380,000 customers in Florida and more than 210,000 in Alabama were without power, according to Poweroutage.us.
Ahead of the worst conditions, caravans of repair trucks moved through Pensacola and Navarre to staging areas in anticipation of outages, reporters on the scene said.
Water service to buildings was suspended.
Isaias rapidly intensified over record-warm Gulf waters heated by climate change, becoming the first hurricane to strike the US mainland since Milton in 2024.
Florida Governor Ron DeSantis told a press briefing that “we’ve got a massive amount of supplies and personnel ready to respond once the storm hits”.
US President Donald Trump called off plans to attend a college football game between the University of Georgia and the University of Alabama in Tuscaloosa, Alabama, because of the hurricane.
Mandatory evacuation orders remained in force in several Florida counties, while forecasters said impacts would be felt across a broad swathe of the southeastern United States.
Storm surge, combined with the tide, was expected to inundate areas that are normally dry, with the NHC warning water could climb as high as 2.7m near the Alabama-Florida border.
Heavy rain was also forecast to bring flash flooding and cause rivers to spill over their banks.
Two airports in northwestern Florida have suspended operations.
A man puts shutters on his home before the arrival of Hurricane Isaias in Pensacola, Florida
Meteorologists said Isaias’s late emergence this season largely reflects an El Niño of historic strength.
El Niño — the warm phase of the El Niño -Southern Oscillation (ENSO) — tends to generate strong vertical wind shear over the Atlantic, a hostile setup that can rip developing systems apart.
“We have been seeing basically nearly record strong shear throughout the Atlantic Basin this year and that is consistent with what we’d expect to see with a strong El Niño event,” Michael Fischer, of University of Miami’s Rosenstiel School of Marine, Atmospheric and Earth Science, said.
In the Pacific Ocean, however, El Niño often has the reverse impact, reducing shear and helping storms grow.
The Pacific has already produced several hurricanes this year, some of which reached maximum Category Five strength.
“Sea surface temperatures in the Gulf of Mexico are in record territory because of fossil fuel-driven climate change,” Marc Alessi, a climate scientist with the Union of Concerned Scientists, said.
“Isaias was able to tap into all of that energy in the ocean to develop into a major hurricane,” he added.
Climate Central, a nonprofit, said Gulf of Mexico waters are about 1.4C warmer than the pre-industrial average. Kristina Dahl, the group’s vice president for science, said Isaias “formed over waters that were 600 times more likely to be that temperature because of climate change”.
Dahl also said storm surge risks are amplified because climate change has lifted sea levels by about 16cm in the region, meaning surge rides atop a higher baseline.
Warming is also tied to heavier rainfall, as hotter oceans and air allow hurricanes to hold and release more moisture.
Isaias also disrupted offshore energy operations in the Gulf of Mexico, prompting evacuations from platforms and rigs.
About 71% of the region’s oil production had been temporarily halted — nearly 1.5 million barrels a day removed from the market — according to the Marine Minerals Administration.
About 59% of gas production was also suspended.
