Introduction to the Hurricane Season
The long lull in tropical activity, right at the peak of hurricane season, has flummoxed meteorologists. Mid-September is the peak of the peak, yet the Atlantic has been quiet for 19 days straight, as of Tuesday.
In the modern satellite era since 1966, “we’ve never seen a shutout” during this very active “window of the season, when on average 4 named storms and 2 hurricanes form each season,” wrote Michael Lowry, a hurricane specialist at WPLG-Ch. 10, in a tropical weather newsletter.
"With this extended lull at the peak," Lowry said, "the 2025 hurricane season is quickly running a deficit and as of today overall activity is almost 50% below average.”
Factors Contributing to the Lull
Lowry and others have some ideas as to what’s going on. “The main thing that I’m seeing is that the Bermuda-Azores High … has been much stronger,” Lowry said.
The Bermuda-Azores High is a semi-permanent, high-pressure system that sits over the Atlantic, often shifting east or west. As hurricanes travel west from Africa, the high can block them from arcing north. But it changes position on a regular basis, steering the path of each storm.
"Typically in September the Bermuda-Azores High weakens. That’s usually when you see things really ramp up in the Atlantic. We’ve seen anything but that. It’s one of the strongest Azores Highs that I’ve seen.”
The high also has been positioned farther south and west than normal, which has pulled cool dry air from northern latitudes down into the tropical Atlantic, killing storms. “The would-be storms are effectively starved,” Lowry said.
This map, based on data from 1944 to 2020, shows hurricane and tropical storm activity peaking in late August and September. (Courtesy National Hurricane Center)
Jet Stream Power
Lowry said we’ve also had a stronger-than-normal dip in the jet stream over the eastern U.S. and western part of the Atlantic. That dip has brought strong upper level winds that scissor with low level trade winds. The result is wind shear.
"Wind shear, which rips the top off storms, has also been stronger than expected," said Carl Erickson, senior meteorologist at Accuweather.
He said prolonged strong jet stream dips like this one are normally something we see in November and December.
September is when storms should be forming off Africa, said Erickson, but the systems that had potential have been neutralized by dry air.
The Role of Saharan Dust
According to Erickson, there’s another factor at play.
"There have been quite large areas of dry, dusty air, a lot of Saharan dust coming across the Atlantic as well. That’s has helped to really put a lid on tropical development in the past month or so," he said. "There have been really prolonged periods of dust. Usually you get a bout of that, but this has been kind of continuous.”
There’s still some mystery to the lull.
The La Niña trend should have been more conducive to storms, and the sea-surface temperatures have been high enough to drive storms as well. And thunderstorms have not been forming well around the systems that have developed. Why?
"I think it’s going to take us some time to unpack," Lowry said.
The jet stream position and strength is a weather pattern as opposed to a climate pattern, he said.
Those are short-term changes that are very hard to predict as the season begins.
"You never really know what the weather pattern is going to be like. What if that was in July instead of September? It would be a different story than what we’re talking about.”
This system, active on Sept. 6, was nullified by dry air that flowed down from the north, leading to one of the quietest peak hurricane periods in years. (Courtesy NHC)
Change Ahead
"We’re starting to see that dry air lessen a little bit," Erickson said.
Wind patterns are becoming less hostile and dust is dissipating.
"We do anticipate a little more active period coming up here," he said.
There are currently two systems in the Atlantic that could ramp up in the next week. If one strengthens into a tropical storm, most models have it curving north before reaching the U.S.
"Unlike previous systems, the tropical wave is accompanied with a decent envelope of showers and thunderstorms," wrote Lowry on a blog post.
Whether the lull will continue into October is up for debate.
Conclusion
The 2025 hurricane season has been unusually quiet, with a 19-day lull in tropical activity at the peak of the season. The Bermuda-Azores High, jet stream power, and Saharan dust have all contributed to this lull. While there is still some mystery to the lull, meteorologists are starting to see changes in the weather patterns that could lead to a more active period in the coming weeks.
FAQs
Q: What is the Bermuda-Azores High and how does it affect hurricanes?
A: The Bermuda-Azores High is a semi-permanent, high-pressure system that sits over the Atlantic, often shifting east or west. As hurricanes travel west from Africa, the high can block them from arcing north.
Q: What is the role of the jet stream in hurricane formation?
A: The jet stream can bring strong upper level winds that scissor with low level trade winds, resulting in wind shear that can rip the top off storms.
Q: How does Saharan dust affect hurricane formation?
A: Saharan dust can help to put a lid on tropical development by bringing dry, dusty air into the tropical Atlantic.
Q: Will the lull in hurricane activity continue into October?
A: It is uncertain whether the lull will continue into October, but meteorologists are starting to see changes in the weather patterns that could lead to a more active period in the coming weeks.
Originally Published: September 16, 2025 at 4:22 PM EDT
