Back in April, scientists read the tea leaves—or, more accurately, piles of data—and predicted above average hurricane season There were nine or ten named storms over the summer and fall, four of which could reach major severity. However, the hurricane season ended Sunday with none making landfall in the United States for the first time in a decade. It was extraordinary in a good way, but the season was extraordinary in many bad ways.
So how did the US, which was hit by Hurricane Helen and four other tropical cyclones last year, avoid disaster even as the Caribbean suffered greatly from Melissa in September?
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First, forecasters could make such forecasts in April by taking several factors into account. Hurricanes are atmospheric engines fueled by warm water, and the Atlantic Ocean has gotten downright hot lately, meaning more energy for stronger storms. “The main factor heading into the season was very, very warm ocean temperatures, either record in parts or near record,” said Brian McNoldy, researcher hurricane scientist at the University of Miami.
Forecasters also took into account how the Pacific Ocean off the coast of South America switches between abnormally warm (El Niño) and cold (La Niña) cycles or remains neutral, as it has done this hurricane season. The El Niño pattern typically reduces hurricane activity by creating vertical wind shear over the Atlantic, which prevents storms from growing, while La Niña encourages them by reducing those winds.
But as hurricane season unfolded, nature revealed an unexpected twist. High in the atmosphere, air currents create something called the jet stream, which contains waves. The part of the wave that rises is called the crest and is associated with more favorable weather. The part that dips to the south is called a depression, which is associated with inclement weather.
In August, September and October—when hurricane season really hits its stride as oceans warm throughout the summer—there was less ridge activity than usual around the southeastern U.S. In fact, it looked more like a depression. This created a counter-clockwise wind movement at the mid-level of the atmosphere where hurricanes rotate. This in turn acted as a kind of force field that pushed hurricanes away from the mainland and back out to sea. “As they approached the East Coast, we had an anomalous influence during this hurricane season where this anomalous trough more or less directed them north,” McNoldy said.
However, the island states of the Caribbean are not so lucky. Hurricane Melissa died minimum 45 people in Jamaica and then marched through Cuba, Haiti and the Dominican Republic. Slowly crossing the Atlantic, he fed on warm waters consisting of 900 times more likely due to climate changeincreasing wind speed by 10 mph. (This may not seem like much, but it increases the potential damage exponentially.) Additionally, a hurricane is such a powerful force that it churns up the sea, bringing colder waters to the surface, which usually reduces the amount of fuel available. But the region Melissa was traveling through was also anonymously warm at great depths, so whatever the storm brought to the surface would still overwhelm it.
All that fuel helped the storm “rapidly intensify,” which is defined as an increase in maximum sustained wind speeds of at least 35 mph in a day. In fact, Melissa underwent a phenomenon called extremely rapid intensification: her speed doubled from 70 mph to 140 mph in just 18 hours. Its maximum speed is 185 mph, making it the second strongest Atlantic hurricane on record and the first most powerful at landfall.
This is where the 2025 hurricane season will be exceptional. While only five hurricanes formed in the Atlantic—half the projected number—four of them, including Melissa, reached Category 5. (The average number of named hurricanes per season is seven.) That means 80 percent of hurricanes managed to do so this year, compared with an average of 40 percent. So while this was the first year since 2015 that a hurricane did not make landfall in the United States, it was only the second year in recorded history that there were three or more Category 5 storms.
It's a wake-up call from climate change: The hotter the oceans get, the more fuel fuels storms. Yes, in a few years this atmospheric force field may help the US avoid landfall, but hurricanes that make it to land will only become more powerful and destructive from here.
