North Atlantic hurricane forecasts trimmed slightly but outlook clouded by uncertainty

By Carlos Pallordet

July 10 - (The Insurer) - Current predictions point to an average or slightly above-average North Atlantic hurricane season but uncertainty remains high

In its most recent update, released on July 9, Colorado State University (CSU) called for an above-average season, with 16 named storms, eight hurricanes, three major hurricanes and an accumulated cyclone energy (ACE) value of 140.

This marks a slight decrease from its previous forecast on June 11, which projected 17 named storms, nine hurricanes, four major hurricanes and an ACE value of 155. That forecast had matched CSU's initial pre-season outlook issued on April 3.

CSU attributed the downward revision to both observed and anticipated high levels of wind shear in the Caribbean, noting that elevated shear in June and July is typically linked to less active hurricane seasons.

London-based forecaster Tropical Storm Risk (TSR) also lowered its predictions for the 2025 Atlantic hurricane season on July 8.

TSR’s latest outlook now matches its initial pre-season forecast from December 2024, projecting 15 named storms, seven hurricanes and three major hurricanes.

However, contrary to CSU, which still expects a slightly above-average season, TSR's figures are in line with the 30-year norm.

The average hurricane season between 1991 and 2020 comprised 14.4 named storms, 7.2 hurricanes and 3.2 major hurricanes (of Category 3 or greater intensity), with an ACE index of 72 to 111.

Forecasters such as North Carolina State University, Mexico's Servicio Meteorológico Nacional and the University of Arizona have provided ranges with midpoints similar to TSR's forecast, pointing to storm activity in line with this 30-year climate norm.

But others including The Weather Company, UK Met Office and the National Oceanic and Atmospheric Administration are calling for an above-average season, in line with CSU.

Specifically, NOAA’s outlook, issued on May 22, anticipates a 60% chance of “above-normal” hurricane activity in the Atlantic basin for the 2025 season, predicting 13 to 19 named storms, of which six to 10 may develop into hurricanes, including three to five major hurricanes.

On average, the 10 sources tracked by The Insurer are predicting 15.6 named storms, 7.8 hurricanes and 3.4 major hurricanes, slightly above the 1991-2020 climate norm.

In a report released at the end of May, Munich Re noted that the differences between predictions among researchers for 2025 are considerable and greater than usual, driven by water temperatures in the tropical North Atlantic and the current status of the El Niño–Southern Oscillation (ENSO) in the equatorial Pacific.

Munich Re said that higher sea surface temperature anomalies are expected to be greater than those in the main development region in the tropical North Atlantic between Africa and the Caribbean, as a warmer Gulf can rapidly intensify cyclones as they pass over the region.

Elsewhere, the ENSO climate pattern is currently in a neutral phase. While El Niño phases tend to limit hurricane activity in the North Atlantic, both neutral and La Niña conditions (which are currently considered to be the most likely scenario for the main phase of the 2025 season) are conducive to cyclone development.

"It’s harder to make predictions for the hurricane season this year compared to last year, as the ENSO phases and development of water temperatures are still very unclear. In any case, diligence is called for, since the latest observations hardly indicate a quiet storm season," said Anja Rädler, meteorologist and climate expert at Munich Re.

The 2024 Atlantic hurricane season was exceptionally active and became the third-costliest on record, surpassed only by 2017 and 2005.

It featured 18 named storms, 11 hurricanes and five major hurricanes.

Among the latter, two hurricanes reached Category 5 intensity – Beryl and Milton – marking the first season since 2019 to feature multiple Category 5 hurricanes.

The next TSR forecast update for the 2025 North Atlantic hurricane season is scheduled for August 5. CSU will release its next seasonal update on August 6. Meanwhile, NOAA’s Climate Prediction Center also plans to update its 2025 Atlantic seasonal outlook in early August.

The Atlantic hurricane season officially runs from June 1 through November 30. Tropical Storm Andrea – the first system of the 2025 season – formed on June 24, marking the latest start to an Atlantic season since 2014.