by Jeff Masters, Yale Climate Connections
June 3, 2026
In September 2024, heavy rains in excess of eight inches (203 mm) poured down on portions of Central America and southern Mexico.
The rains, a warning sign of what was to come, resulted from a sprawling low-pressure weather system known as a Central American Gyre, which developed over Central America and the adjacent waters of the Caribbean, Gulf of Mexico, and Eastern Pacific. After festering for three days, the lobe of the Central American Gyre over the northwestern Caribbean split off from the main low and developed into Hurricane Helene, one of the most notorious Atlantic hurricanes of all time. Helene’s rampage across the western Caribbean and through the Southeast U.S. killed 217 people and caused $81 billion in damage, making it the seventh-costliest weather disaster in world history.
Helene was one of three named storms that were spawned by a Central American Gyre in 2024, along with Tropical Storm Alberto and Hurricane Rafael. A number of devastating hurricanes have been spawned by these gyres in recent years, including Cat 4 Opal of 1995, Cat 4 Michelle of 1999, Cat 5 Wilma of 2005, and Cat 5 Michael of 2018. This naturally gives rise to the question: How is climate change affecting the propensity of Central American Gyres to spawn hurricanes? The answer: As far as we can tell, the gyres and Central American Gyre-spawned hurricanes are not increasing in frequency, but it is possible that climate change could cause an increase in the future.
Read more: A large Central American low could spawn Helene
What is the Central American Gyre?
The Central American Gyre is a type of monsoon low. It is a weak but expansive area of surface low pressure that typically takes many days to organize but can persist for two weeks or more across Central America and adjacent oceans, including the western Caribbean and southwest Gulf of Mexico. They are most common in May, June, September, October, and November. The gyres often spin off smaller circulations that can become full-fledged tropical cyclones over the Atlantic or Eastern Pacific, but only about one-third of Central American Gyres end up spawning a named storm. Due to the prevalence of these gyres either early or late in the hurricane season, when sea surface temperatures are cooler, and wind shear is higher, the hurricanes it spawns tend to be weaker than those occurring during the peak of the hurricane season.
Central American Gyre climatology
According to National Hurricane Center hurricane forecaster Philippe Papin (see his great article, A Climatology of Central American Gyres), during the period 1980-2010, 42 Central American Gyres were classified (about 1.4 per season). These gyres spawned a total of 14 tropical cyclones, some of them in the Eastern Pacific. The record for most Atlantic named storms being spawned by Central American Gyres in a year is three, set in 2024, 2005, and 1998. In addition, Hurricane Milton of 2024 was spawned by a tropical wave that interacted with the remnants of a Central American Gyre (which had earlier helped spawn Hurricane Helene in the Caribbean and Hurricane John in the eastern Pacific).
According to an email from Papin, La Niña events tend to favor more Central American Gyres as they weaken the low-level easterly trade wind flow south of Central America, boosting the large counter-clockwise flow of air around the developing gyre (abbreviated as CAG in the following quote): “This is especially common during May-June and September-November when the Eastern Pacific Intertropical Convergence Zone (ITCZ) is shifted more poleward in the shoulder seasons outside of the mid-summer drought over Central America,” Papin wrote. “This pattern favors more low-level southwesterly flow feeding into the elevated heating over the Central American highlands. This elevated heating triggers heavy thunderstorm activity (convection), and the resulting heat release promotes the spin-up of a CAG in the low- to mid-levels over Central America. However, due to the rugged terrain, these winds often intensify only over lower elevations or over open waters, contributing to the large, broad circulations typical of CAGs.”
Papin created a Central American Gyre climatology covering 1980-2010. It notes the following Atlantic named storms the gyres spawned between 1995 and 2010:
1995: Hurricane Opal, Hurricane Roxanne
1996: Hurricane Lili, Hurricane Marco
1998: Hurricane Earl, TS Frances, TS Hermine
1999: Hurricane Irene
2001: Hurricane Michelle
2005: Hurricane Stan, Hurricane Wilma, TS Gamma
2007: TS Barry
2008: TS Arthur, TD Sixteen
2009: Hurricane Ida
2010: Hurricane Alex, TS Nicole
Using the National Hurricane Center’s end-of-season tropical cyclone reports as reference, here is my update of Central American Gyre-spawned named storms for the period 2011-2025:
2013: TS Andrea
2017: Hurricane Nate, TS Philippe
2018: Hurricane Michael
2019: TS Nestor
2020: TS Cristobal
2021: TS Claudette
2022: TS Alex
2024: TS Alberto, Hurricane Helene, Hurricane Rafael
There were no Central American Gyre-spawned named storms in 2025.
How will climate change affect Central American Gyres?
Regarding how climate change might influence these gyres, Papin had this to say:
“It’s likely that individual events will produce more rainfall due to higher moisture availability in a warmer atmosphere. As for changes in their overall frequency or duration, that remains an open question. If a warming planet shifts the [Eastern Pacific Intertropical Convergence Zone] ITCZ more poleward, it could increase the risk of CAG events over Central America by enhancing moist southwesterly flow into the region, promoting elevated convection over higher terrain.”
However, the future of the ITCZ, and thus Central-American-Gyre-spawned hurricanes, is murky. A 2025 study, Response of Tropical Climate and Extreme Precipitation to Ocean Temperature in Convection‐Permitting Aquaplanet Simulations, said: “Climate projections disagree on key aspects of the intertropical convergence zone (ITCZ), such as whether it will expand or contract, intensify or weaken, shift location, or remain in place.”
So for now, how the future incidence of Central American Gyre-spawned hurricanes might change is unknown.
Bob Henson contributed to this post.
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