Why this ‘weird’ U.S. hurricane season is still a troubling one

This year marks the first time in a decade that there hasn’t been a hurricane landfall in the United States.

That’s true even as several massive and menacing storms formed, many tracking perilously close to the United States. The Atlantic season, which officially ends Nov. 30, produced Hurricanes Erin and Imelda, as well as Melissa, one of the most powerful Atlantic hurricanes on record that devastated Jamaica. But it didn’t take a hurricane landfall to have dangerous consequences in the United States.

In July, the remnants of Tropical Storm Barry contributed to deadly and devastating flooding in the Texas Hill Country and Tropical Storm Chantal caused destructive and fatal flooding in North Carolina, amid a global trend toward a moister atmosphere.

“This season was a weird one,” said Philip Klotzbach, a senior hurricane research scientist at Colorado State University.

Three storms catapulted to Category 5 intensity – the second-highest number on record for storms of that intensity within a single season. Four storms reached at least Category 4 strength. Four storms also rapidly intensified – Erin, Gabrielle, Humberto and Melissa – meaning that their winds accelerated by at least 35 mph in a day.

Klotzbach emphasized that even a small number of intense storms could be more hazardous than many milder ones.

“If those massive storms happen to hit something, the potential damage is a lot higher,” he added.

In total there were 13 storms – one less than the long-term average.

Early forecasts predicted as many as 19 storms this season, well above the number that have since formed. The exact number of storms is challenging to predict months in advance, so scientists often focus more on accumulated cyclone energy , which is a measure of storm wind strength and duration.

Klotzbach added that the year had slightly more ACE than normal, even with fewer storms, underscoring the strength of the systems that did form.

No tropical activity is expected in the next week, according to the National Hurricane Center.

Fueling the monster storms

This year’s powerful array of storms was linked by a factor that lies deep below the ocean – high ocean heat. This excess heat is fuel for storm intensification.

More than 80% of the Atlantic was covered by above-average ocean heat during the season, the third-highest amount on record since records began in 1958, behind only 2023 and 2024.

Part of a concerning trend, the near-record high ocean heat – in the top 10 percent of historical observations – covered almost 40% of the Atlantic basin. Before 2022, this metric had never been higher than 30%, making the recent ascension of ocean heat particularly notable.

Instead of churning up cooler waters from below, violent storm winds instead found more warm water beneath the surface, enabling storms to remain or become more intense.

But high ocean heat alone doesn’t cause storms to form.

A tropical storm begins as a cluster of thunderstorms. When that cluster taps into an unstable atmosphere – one in which warm, buoyant air is rising – it can organize and intensify.

That instability is driven by the temperature difference between the warm ocean surface and the much colder upper atmosphere.

This vertical gradient, known as the lapse rate, helps set what experts call the potential intensity – the upper limit on how strong a hurricane’s winds can get.

“The thing that really powers the hurricane is how fast you can transfer heat from the ocean to the atmosphere. The bigger the temperature difference, the faster you can transfer heat. The faster you can transfer heat, the more powerful the hurricane can be,” said Kerry Emanuel, a professor of atmospheric science at Massachusetts Institute of Technology.

But that gradient was not particularly strong this year in some parts of the Atlantic, illustrating why this temperature difference matters more than the sea temperature alone. And it forms part of the reason a warming planet may have fewer tropical storms, but more intense ones overall.

“This past summer, the sea surface temperatures across much of the tropical Atlantic were warmer than normal, which is part of what led people to predict that there would be a very busy season,” Emanuel said.

But because the air above was also warm, potential intensity was lower than normal. That was partly responsible for why there were fewer than normal storms originating in certain parts of the tropical Atlantic, he said.

Then there was the Caribbean, where monster Hurricane Melissa formed. There, the potential intensity was high.

There’s little to suggest that this extra ocean heat will subside in 2026, which means it will probably be a key factor again next hurricane season.

However, one climate driver that contributed to conditions that were more conducive to hurricanes in 2024 and 2025 – La Niña – will probably fade early next year.

It’s unusual to have at least two consecutive years without a hurricane landfall in the United States. It has happened only six times since records began in 1851, the last times in 2009 and 2010.