Scientists say hurricanes driven by human-caused warming — like Hurricane Melissa — are increasingly exceeding the Saffir‑Simpson scale’s limits. Some experts propose a hypothetical Category 6 around 192 mph, while others caution that changing the scale complicates historical comparisons. Studies estimate Melissa was made four times more likely by climate change and had its winds boosted by about 10–11 mph, pushing peak sustained winds toward roughly 185 mph. Researchers also urge that flood risk and emissions cuts be central to future planning.
Category 6? Scientists Warn Hurricanes Like Melissa Are Outgrowing the Saffir‑Simpson Scale
Scientists say hurricanes driven by human-caused warming — like Hurricane Melissa — are increasingly exceeding the Saffir‑Simpson scale’s limits. Some experts propose a hypothetical Category 6 around 192 mph, while others caution that changing the scale complicates historical comparisons. Studies estimate Melissa was made four times more likely by climate change and had its winds boosted by about 10–11 mph, pushing peak sustained winds toward roughly 185 mph. Researchers also urge that flood risk and emissions cuts be central to future planning.
22:42, 03.11.2025Environment
Scientists warn storms like Melissa are pushing beyond the Saffir‑Simpson scale
As Hurricane Melissa moved into the Atlantic after battering Jamaica and Cuba, some climate scientists said the storm reinforced a worrying trend: hurricanes fueled by human-caused warming are becoming stronger, intensifying faster and posing greater threats than the existing Saffir‑Simpson Hurricane Wind Scale was designed to capture.
The Saffir‑Simpson scale, which rates storms by maximum sustained wind speed and caps at Category 5 ("catastrophic") for winds of 157 miles per hour and above, may no longer reflect the full range of modern hurricane intensity. Researchers note that five tropical cyclones since 2013 would have qualified as a hypothetical “Category 6” if such a designation existed.
Some climatologists have proposed a Category 6 threshold near 192 mph of sustained wind. Dr. Michael Mann, Presidential Distinguished Professor of Earth and Environmental Science at the University of Pennsylvania, said Melissa "came close" to that level and that post-season reanalysis could even revise estimates upward.
“As long as we're using wind-based metrics, it simply doesn't make sense — mathematically, fiscally, or sociologically — to artificially cap the scale at five any more,” Mann said.
Others urge a broader rethink. Dr. Katharine Hayhoe, Chief Scientist at The Nature Conservancy, argues the scale should consider precipitation and flooding — the primary driver of hurricane-related economic losses — not only wind. "Flooding damage can be as large or larger than wind damage," she said, calling for a possible full revision of how we classify storms.
Not all experts favor adding a new category. Colorado State meteorologist Dr. Phil Klotzbach said he saw little practical benefit: "Uninhabitable for weeks or months is about as bad as it gets with hurricanes." Dr. Zachary Handlos of Georgia Tech warned that changing the long‑standing scale would complicate historical comparisons unless past storms are reanalyzed to the new standard.
Scientific studies underscore the role of human-driven warming in making extreme storms more likely. An Imperial College London analysis found Melissa was made about four times more likely by anthropogenic climate change and estimated an increase of roughly 11 mph in its peak winds. Independent analysis by Climate Central meteorologist Daniel Gilford estimated that extra ocean warming raised Melissa's intensity by roughly 10 mph, pushing its maximum sustained winds toward about 185 mph.
Warmer sea surface temperatures are a key factor driving stronger winds and faster intensification. Experts note that the world has warmed roughly 1.3°C since pre‑industrial times, a level of warming that will influence storm behavior for decades. While some degree of stronger storms is already locked in, scientists emphasize that rapid and sustained cuts to greenhouse gas emissions can reduce how much worse hurricanes become in the future.
Takeaway: Whether through an added "Category 6," a wholesale revision of the Saffir‑Simpson scale, or new metrics that include rainfall and surge, researchers say classification systems must evolve to reflect the realities of a warming world and to help communities better prepare for increasingly extreme storms.