Guy Carpenter has released its update on the 2025 Atlantic hurricane season, reporting generally average activity through late August. Six named storms have formed so far, which is slightly below the 1993-2024 climatological mean for this point in the season.
Accumulated cyclone energy, a measure that considers both the intensity and duration of tropical cyclones, is running slightly above normal for the year. This is largely due to the strength and longevity of Hurricane Erin. Most other storms in the Atlantic this year have been weak and short-lived, with limited impact.
The subdued start to the season has been attributed to two main atmospheric variables. Dry Saharan air and persistent wind shear have limited the intensification of tropical systems.
Despite these factors, sea surface temperatures remain above average across the southwestern Atlantic and the Gulf of Mexico. This temperature pattern is generally favorable for the development and strengthening of storms closer to land.
Looking ahead to September, Guy Carpenter notes that the climatological peak of the Atlantic hurricane season is approaching. However, limited new tropical cyclone activity is expected during the first third of the month.
The outlook suggests that this lull in activity may be temporary. Once the current unfavorable atmospheric pattern shifts, the generally above average sea surface temperatures across the Atlantic are expected to support an increase in storm activity.
The report also points out that a large area of cool sea surface temperature anomalies in the western Atlantic is the result of Hurricane Erin upwelling cooler water to the surface. Cooler than normal conditions in the American Southeast have contributed to this anomaly, but a gradual warming of Erin’s “cold wake” is anticipated as September progresses.
Forecasts from nine meteorological research organizations indicate that the 2025 Atlantic hurricane season could see an average of 16 named storms, eight hurricanes, and three major hurricanes. These projections are above the long-term average but are expected to fall below the levels recorded in 2023 and 2024.
The insurance industry continues to monitor the financial impact of recent hurricane seasons. In 2024, insured natural catastrophe losses reached $137 billion globally, marking the fifth consecutive year with losses exceeding $100 billion, according to Swiss Re.
Guy Carpenter also highlights recent forecasts from NOAA regarding the El Niño Southern Oscillation. There is an increasing likelihood of a transition to a weak La Niña in the latter half of the hurricane season. La Niña conditions typically reduce wind shear across the Atlantic, which can enhance tropical cyclone activity.
The combination of warm ocean waters and the potential for weak La Niña conditions suggests that the most active period of the 2025 Atlantic hurricane season may occur later than the usual mid-September peak.
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