The largest hurricane to hit the US mainland this year, Hurricane Helene hit the Florida coastline late Thursday as a Category Four storm, devastating much of the Big Bend area of the northern part of the state, then moving rapidly northward as a huge rainstorm, causing flooding and other weather-related damage in as many as 15 states. The death toll is already at 42, and expected to rise considerably.

The geographic extent of the hurricane, well over 500 miles in diameter, with a track spanning 1,000 miles across the southeastern US, was as remarkable as its sudden growth in intensity. What had been a tropical storm as it passed northward along the Yucatán Peninsula of Mexico Tuesday rapidly intensified as it moved over the Gulf of Mexico, whose waters are at record temperatures as a consequence of global warming.

Helene became a full-blown hurricane on Wednesday, and grew stronger at an amazing pace, going from Category One to Category Four, the second-highest level, in less than two days. By the time the eye made landfall near Perry, Florida, Helene’s top winds were hitting 140 miles per hour and the storm surge from the Gulf of Mexico reached 15 feet.

One of the small towns at the center of the storm, Keaton Beach, Florida, suffered near-total damage, with an estimated 90 percent of the homes there destroyed. The hurricane threw boats out of the water like projectiles, landing them on top of houses or smashing them on pavement in the town center.

According to media reports, very few of those living in the hardest hit region of Florida have flood insurance, because repeated strikes by powerful hurricanes have driven up insurance rates to unaffordable levels.

There was heavy damage from storm surge from the Sarasota area, south of Tampa Bay, all the way north and west along the Gulf Coast to Pensacola. Winds knocked out power lines across a vast area, with 4 million people without electricity as of Friday night, with the worst flooding reported in Georgia, North Carolina, South Carolina, Virginia, Tennessee and Kentucky.

Helene moved from the coast to the Tallahassee, Florida, area, then northwards across Georgia to the Atlanta metropolitan region, which suffered its greatest single-day rainfall, nearly 12 inches. It then crossed the Appalachian Mountains, making a left turn that placed the remnants of the storm near Louisville, Kentucky, by late Friday.

After a decade-long lull after Hurricane Katrina devastated New Orleans and much of the Gulf Coast in 2005, the Florida panhandle and Big Bend region has been hit by seven named hurricanes since 2016, as well as a similar number of tropical storms. Of these, Hermione in 2016, Michael in 2018, Idalia in 2023, and Debby and now Helene in 2024, hit the Big Bend area head on.

Hurricane Michael, a rare Category Five storm, killed 50 people and caused $18 billion in damage in 2018, while the other storms were weaker and caused less damage. The death toll from Helene is already 42, and is likely to go much higher after rescue and recovery efforts are completed, and the damage is likely to be far higher, since Helene is much wider in area than Michael, although slightly less intense.

According to the National Weather Center, a Category Four storm is one with sustained high winds of 130 to 156 miles per hour. According to this definition: “Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.”

Hurricane Helene is a social and economic disaster, not merely a natural one. Property insurance premiums in Florida soared 45 percent from 2017 to 2022, bringing the average annual premium for a Florida homeowner to $5,500, more than twice the US average. In particularly flood-prone areas, insurance rates have approached $20,000 a year, and most working people have to face the mounting risk of devastating storms without any insurance protection.

Many major insurance companies have simply pulled out of the state of Florida altogether, concerned that a direct hit by a storm the size of Helene on a major metropolitan area such as Miami or Tampa-St. Petersburg would cause losses in the hundreds of billions of dollars. As it happened, Helene struck one of the least populated and least developed areas of the Florida Gulf Coast.

The Republican-controlled state government, headed by ultra-right Governor Ron DeSantis, pushed through a property insurance “reform” bill in 2022 to cut costs to insurance companies and penalize what the insurers called “frivolous” lawsuits by consumers.

DeSantis is a leading denier of climate change. His predecessor as governor, Rick Scott, now a US senator, flatly refused in a cable television interview Friday to concede that climate change was the main factor in driving up the intensity and scale of contemporary hurricanes.

Helene was unusual, not only in its width and strength, but in how it behaved after coming ashore. Rather than dropping off rapidly in intensity as it moved over land, Helene remained at hurricane strength into central Georgia and South Carolina, and still remained a powerful “once-in-a-generation” rainstorm as it moved into the Appalachian Mountains, according to one weather service.

Water levels in rivers running out of the Appalachian highlands, either east to the Atlantic or west and north to join the Ohio and Mississippi, were already high because of previous storms, and flash flood emergencies were declared in counties in western North Carolina, western South Carolina and northern Georgia, including the Atlanta metro area, on Friday morning.

The combination of the ferocity of the storm and the topography of the Appalachian region produced striking scenes Friday, as the city of Asheville, the largest in the western tip of North Carolina, saw heavy flooding of the River Arts District.

In Unicoi County, just north of Asheville across the Tennessee line, Unicoi County Hospital became an island surrounded by floodwaters, with boats deployed for evacuation. After the floodwaters became too dangerous, the hospital’s emergency rescue helicopter had to be used to take patients and staff out rather than bring people in. The last 50 patients and staff were evacuated by air to neighboring Johnson City.