Overview
Despite an active number of named storms, the 2025 North Atlantic hurricane season has been characterized by below-average power.
- Gabrielle, the season’s seventh named storm, formed on September 17, which is two weeks later than the average formation date of September 3.
- Hurricane Erin was the season's first hurricane and first major hurricane, named on August 11. This timing is average for a first hurricane but early for a first major hurricane.
- Accumulated Cyclone Energy (ACE) thus far is below average. As of September 19, the season's ACE is 42, which is only 62% of the average value of 67 for this date.
It only takes one storm to define a hurricane season. However, below-average power and a below average number of storms have left many wondering how the 2025 hurricane season will shape up.
This season is running slightly behind schedule in terms of storm formation, according to data tracked by the National Oceanic and Atmospheric Administration (NOAA). The seventh named storm of the season, Tropical Storm Gabrielle, formed on Sept. 17. By comparison, the 1991-2020 climatological average for the formation of the seventh named storm is Sept. 3.
Progress of an average Atlantic hurricane season (1991-2020)
Data source: NOAA National Hurricane Center, Tropical Cyclone Climatology, 2025
However, it’s not just how many storms occur but also their intensity that characterizes the hurricane season. This season did produce an intense storm in Hurricane Erin, which was named on August 11. Erin holds the distinction of being both the first hurricane and the first major hurricane of the 2025 season.
While the timing for the first hurricane was average, its intensification into a major hurricane was earlier than average, demonstrating that the conditions needed for rapid development do exist in the Atlantic.
Why no single storm has defined the 2025 Atlantic hurricane season
The most scientifically significant feature this season is the below average Accumulated Cyclone Energy or ACE. ACE is a metric used by meteorologists to measure the total power and duration of all tropical storms and hurricanes over a season.
As of September 19, the ACE for the North Atlantic basin stands at 42. The long-term average for this point in the season is 67, meaning the current season has generated only 62% of the energy expected. A potential cause for this lower-than-average ACE is the presence of unfavorable atmospheric conditions, particularly wind shear and dust storms.
Wind shear is highly disruptive to tropical cyclones. It tilts the vertical structure of a developing storm, preventing it from organizing and strengthening, just like it did with Hurricane Tammy. Furthermore, periodic outbreaks of the Saharan Air Layer (SAL) can push dry, dusty air from Africa out over the Atlantic, starving potential storms like Tropical Storm Hermine of the moisture necessary for their formation and sustenance. These inhibiting factors may have suppressed the intensity and longevity of this season’s storms, leading to the energy deficit we see today.
It is critical to remember that the Atlantic hurricane season officially extends until November 30, which leaves over two months for powerful storms to develop in the warm waters of the Caribbean Sea. History has shown that devastating, late-season hurricanes can form with little warning, which is why it is crucial for coastal residents to remain vigilant.
Cotality will continue to monitor the North Atlantic hurricane season, providing updates when available.
Learn more about this year's hurricane season on the Beyond the Forecast webinar.
