Hurricane season in the Atlantic kicked off Monday, and, for the first time in more than a decade, forecasters expect it to be relatively slow.
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The below-average forecast is driven by the expectation that a strong El Niño pattern will develop, which is associated with less hurricane formation in the Atlantic. The opposite is true in the Pacific, however, which should have an active season.
Most hurricanes that make landfall in the U.S. form in the Atlantic, where forecasters at the National Oceanic and Atmospheric Administration predict the year will have just three to six hurricanes (storms are considered hurricanes once winds reach 74 mph) and between eight and 14 named tropical storms.
The forecast does not predict whether storms will make landfall, however.
“It just takes one,” Ken Graham, director of the National Weather Service, said at a news conference last month about the agency’s predictions. He noted that one of the costliest hurricanes of all time, Andrew in 1992, took place in a season with less tropical storm formation than usual.
“Even in a below-average season, even if you have fewer storms, they could be big ones,” Graham said.
NOAA’s forecast is roughly in line with others. A website operated by Colorado State University and the Barcelona Supercomputing Center tracks predictions from 23 hurricane forecasting centers and found that the average predicted was five hurricanes. In a typical year, seven would be expected. Last year, there were five hurricanes in the Atlantic, which was lower than the six to 10 NOAA had projected. In 2024, there were 11, in a year when NOAA had predicted eight to 13.
El Niño is a natural cycle that causes warm surface temperatures in the tropical Pacific Ocean. It affects hurricanes through its influence on vertical wind shear, a term that describes the difference between wind speed or direction at different layers of the atmosphere.
Hurricanes thrive when there’s low wind shear because that allows storms to build a cohesive rotation and to circulate heat and moisture toward the center.
El Niño, however, is associated with higher vertical wind shear in the Atlantic, which disrupts this process. That makes it more challenging for tropical disruptions generated off the coast of Africa to travel across the ocean and strengthen into hurricanes. However, the opposite pattern is true in the Pacific.
“In the central and eastern Pacific, the El Niño reduces the vertical wind shear, essentially the opposite of the Atlantic, which is why we’re expecting an above-average season,” NOAA Administrator Neil Jacobs said at last month’s news conference.
Forecasters expect a strong El Niño to emerge soon. NOAA’s most recent calculations suggest there’s an 82% chance circulation patterns will officially enter the cycle by July and that there’s a 96% chance of El Niño from December through February 2027.
El Niño has significant effects on weather patterns beyond influencing hurricane formation. Importantly, it can exacerbate air temperatures beyond what is normally expected from global warming so could lead to even hotter weather in many parts of the U.S. In the Pacific Northwest, an El Niño summer often exacerbates drought, which is a particular concern this year given the region’s severe snowpack deficit. In the Southwest, meanwhile, El Niño can diminish the early summer monsoon season but bring unusually wet weather in the winter.
NOAA predicts nine to 14 hurricanes in the Pacific this season. Although Pacific hurricanes don’t typically make landfall in the continental U.S., they can cause major weather disruptions.
Hurricane Hilary in August 2023 had been downgraded to a tropical storm by the time it reached the California coast, but its moisture broke rainfall records in four Western states. The same year, Hurricane Dora passed within about 400 miles of Hawaii, churning up winds on the islands that contributed to the Lahaina fire disaster on Maui.
The last hurricane to make landfall in Hawaii was Iniki in 1992, which caused widespread damage on Kauaʻi. The storm famously disrupted the filming of the blockbuster film “Jurassic Park.”
Flooding covers a residential neighborhood in Waialua, Hawaii, on March 20.Mengshin Lin / AP
Several Hawaiian islands, including Maui and Oahu, already dealt with severe flooding this spring, after storms pounded parts of the islands that are usually more sheltered from rain.
A busy storm season could keep Hawaiians on edge — even if a hurricane doesn’t strike directly, it could whip up dangerous winds or bring more severe rain.
