Global warming is making the strongest hurricanes stronger » Yale Climate Connections

In brief: 

• Multiple studies have found that tropical cyclones are becoming stronger worldwide. 
• New so-called attribution studies have linked increased wind speeds to human-caused ocean warming. 
• In the future, scientists expect an increase in the proportion of Category 4 and Category 5 tropical cyclones.

The dangers posed by one of humanity’s greatest scourges – the tropical cyclone – are being significantly increased by human-caused global warming. In fact, one of the more confident predictions about how climate change will affect these great storms — which we will refer to by their Atlantic name when they reach winds of 74 mph (119 km/hr) or greater, the hurricane —  is that the winds of the strongest ones will get stronger. But how much stronger? Are we already seeing this happening? And how do scientists know? 

Spotty data 

People began collecting high-quality, satellite-based global tropical cyclone data only around 1982. The relatively poor quality and short length of the global hurricane database, combined with the natural high variability in hurricanes, make ironclad scientific statements on how climate change is affecting hurricanes difficult. In their Global Warming and Hurricanes explainer, scientists at NOAA’s Geophysical Fluid Dynamics Laboratory wrote, “it is premature to conclude with high confidence that human-caused increases in greenhouse gases have caused a change in past Atlantic basin hurricane activity that is outside the range of natural variability.” Statements like this are often used by climate deniers to downplay climate change risks.

That said, scientists do understand the basics. Hurricanes are heat engines that take heat energy out of the ocean and convert it to the kinetic energy of their winds. A hotter ocean will allow hurricanes to grow more powerful, assuming that the other factors that support intensification, including low wind shear and a moist atmosphere, are present. 

And there is already evidence that the strongest storms are getting stronger. For example, a July 2025 analysis found that human-caused climate change increased the intensity of 2024’s Atlantic hurricanes by 3%-12%. This may seem trivial, but a 5% increase in hurricane winds yields about a 50% increase in damage: Hurricane damage increases exponentially with an increase in winds (see NOAA’s damage multiplier table in Fig. 3)

For 2024’s devastating Hurricane Helene, another study found an 11% increase in winds because of climate change, accounting for 44% of the $81 billion in damage caused by Helene.

An increase in Cat 5 storms globally

High-quality satellite-based data shows an increase in the number of Category 5 storms. Of the 217 Cat 5s globally during the 44-year period 1982 to 2025, 59% occurred in the last half of the period (Fig. 1), and there has been an increase in the number of Cat 5s since accurate global satellite data became available in 1982 (and technically, this is statistically significant at better than the 1% level – meaning that this is a real trend and not random variability). And if we look at the strongest tropical cyclones by ocean basin since 1980 (Fig. 2), the records for nine out of 11 of these ocean basins were set in the last half of the 46-year period ending in 2025.

Five studies showing tropical cyclones are already getting stronger

According to a 2020 paper by MIT scientist Kerry Emanuel, Evidence that hurricanes are getting stronger, global warming should cause an increase in the probability of encountering major tropical cyclone wind speeds (Cat 3 and stronger) of about 7.5% per decade. This finding mirrors the most often-cited study showing that the strongest hurricanes are already getting stronger – a 2020 paper, Global increase in major tropical cyclone exceedance probability over the past four decades. Based on a review of six-hour data points of hurricane strength collected from 1979 to 2017, the study found that the fraction of major hurricane data points increased by 10%. This increase was greatest in the Atlantic, where major hurricanes data points comprised 40% of all hurricanes data points in the most recent 20-year period they studied, compared to 23% during the prior 20 years.

At least four other studies have since also observed that tropical cyclones are getting stronger globally:

• A 2026 paper, Weak self-induced cooling of tropical cyclones amid fast sea surface warming, found that from 1992-2021, Cat 1+ hurricanes globally intensified by 3.9 mph (6.3 km/h) over the 30-year period.
• A 2026 paper, Shortened intensification duration offsets the increase of tropical cyclone lifetime maximum intensity, found from 1982-2023, Cat 3+ hurricanes globally intensified by 8.8 mph (14 km/h) over the 42-year period.
• A 2022 paper, Ocean currents show global intensification of weak tropical cyclones, found that tropical cyclones below hurricane strength strengthened by four mph (6 km/h) per decade over the period 1991-2020, based on ocean current measurements.
• A 2020 paper, Continued Increases in the Intensity of Strong Tropical Cyclones, found from 2007-2019, winds of Cat 1+ hurricanes globally were 4% higher than those from the prior 26 years, when considering the strongest 25%, 10%, and 5% of storms. In the Atlantic, the strength of the strongest 5% of hurricanes increased by about 5%.

Model predictions for the future: a global 5% increase in intensity for 2°C more global warming

A 2020 review paper by 11 hurricane scientists, Tropical Cyclones and Climate Change Assessment: Part II: Projected Response to Anthropogenic Warming, summarized dozens of modeling studies on how hurricanes would respond to 2 degrees Celsius of global warming, relative to 1986-2005 conditions. (Because Earth has been warming at about 0.2 degree Celsius per decade, we’ve already seen about 0.6 degree Celsius of that 2-degree warming.) Globally, in the higher-resolution studies, the median projected increase in lifetime maximum surface wind speeds was about 5%, and the increase in the proportion of tropical cyclones reaching Category 4-5 levels was +13%. For the Atlantic, the 52 models evaluated showed about a 3% increase in lifetime maximum surface wind speed.

New studies evaluate the influence of climate change on hurricanes 

Still in their infancy, attribution studies examining specific hurricanes are now being performed in near real time. These studies evaluate the degree to which climate change influenced a given weather event. 

For example, human-caused climate change increased Hurricane Melissa’s peak sustained wind speeds by 7% (11 mph, or 18 km/h), making 34% of its damages attributable to climate change, according to researchers at the Imperial College of London. Melissa made landfall in Jamaica in October 2025 as the strongest landfalling hurricane on record, with sustained winds of 185 mph (300 km/h). In a separate report, the researchers found that the winds of Category 4 Hurricane Beryl of July 2024 were increased by 10 mph (16 km/h) – a 7% increase – as the storm brushed Jamaica.

World Weather Attribution, an international scientific group, released a report showing that the winds of Florida’s 2024 Hurricane Milton increased by about 11 mph (18 km/h), or 10%, as a result of climate change, a conclusion echoed by researchers at the Imperial College of London, who studied the same storm independently. 

A third organization, France-based climatameter.org, also performs attribution studies shortly after extreme events occur. They found that human-caused climate change could have increased the winds of Hurricane Ian (2022) by 6 mph (10 km/h), Hurricane Beryl (2024) by 5.6 mph (9 km/h), Hurricane Helene (2024) by 3 mph (5 km/h), and Hurricane Melissa (2025) by 5 mph (8 km/h).

A 2024 paper, Human-caused ocean warming has intensified recent hurricanes, found that between 2019 and 2023, the maximum sustained winds of Atlantic hurricanes were, on average, 19 mph (31 km/h) higher because of human-caused ocean warming. A parallel report by Climate Central, a nonprofit scientific research organization, applied the techniques developed in the paper to the 2024 hurricane season, finding that climate change increased maximum wind speeds for all 11 Atlantic hurricanes in 2024 by nine to 28 mph (14-45 km/h).

However, these approaches looked only at how warmer oceans alone influenced storm strength. Rising atmospheric temperatures and moisture can make the tropical atmosphere more stable, counteracting the intensity increase computed using sea surface temperatures alone. 

In an email, the lead author of that study, Daniel Gilford of Climate Central, said that an improved method taking this effect into account had been developed, and using this method, “I expect the 2019-2023 estimates to be about 50% lower, though the amount of damping will vary from storm to storm.” 

In July 2025, Climate Central used this improved method for the hurricanes of 2024, resulting in climate change-driven intensification estimates (Fig. 4) that were about 50% lower than their original estimates. Below is their revised table, published in July 2025, showing a human-caused intensity increase ranging from 3%-12% for 2024’s Atlantic hurricanes:

Climate change expected to generate more “Cat 6” superstrength hurricanes

A paper published in 2024 by hurricane scientists Michael Wehner and James Kossin, The growing inadequacy of an open-ended Saffir – Simpson hurricane wind scale in a warming world, argued that we now need a “Category 6” rating for hurricanes with winds of 193 mph (311 km/h) or greater, because global warming is expected to cause significant increases in maximum potential intensity. The study found that if the climate warms by 2 degrees Celsius (3.6°F) above preindustrial levels – which could happen by midcentury – the risk of such a Category 6 storm in the Gulf of Mexico would double (Fig. 5).

Scientists expect an increase in the proportion of Cat 4 and Cat 5 tropical cyclones

One of the first analyses documenting an apparent global increase in Category 4 and 5 hurricane frequency was published in September 2005, less than a month after catastrophic Hurricane Katrina. Interest in the topic has been keen ever since. Because there are many more Cat 4 and 5 storms than Cat 5 storms alone, there is a higher potential for a change to be deemed statistically significant.

The latest Intergovernmental Panel on Climate Change report, published in 2021, says: “The proportion of intense tropical cyclones (Category 4-5) and peak wind speeds of the most intense tropical cyclones are projected to increase at the global scale with increasing global warming (high confidence).”

Preliminary evidence suggests this shift may already be occurring. A 2022 paper, Trends in Global Tropical Cyclone Activity: 1990–2021, found a 2%/decade increase in the percentage of global hurricanes reaching Cat 4 or Cat 5 strength (Fig. 6). The increase was highest in the Atlantic basin, with a 5% per decade increase.

In a 2019 review paper by 11 hurricane scientists, Tropical Cyclones and Climate Change Assessment: Part I. Detection and Attribution, eight of 11 authors concluded that the balance of evidence suggests that human-caused climate change contributed to the detectable increase in the global average intensity of global hurricanes since the early 1980s. All 11 authors agreed that the balance of evidence suggests that the proportion of all hurricanes reaching Category 4 to 5 strength has increased in recent years; eight of 11 authors concluded that the balance of evidence suggests that human-caused climate change contributed.

A preprint of a 2025 paper that is under review and has not yet been published, Oceanic Warming Has Lengthened Intense Tropical Cyclone Seasons Globally, found that since 1980, the length of the Cat 4 and Cat 5 hurricane season globally has increased by nine to 14 days per decade. The lengthening is characterized by a late end to the season in the Atlantic and an early onset in most of the other ocean basins.

However, though the proportion of Cat 4 and Cat 5 hurricanes globally has increased, the total number did not see an increase between 1990 and 2021, according to a 2022 paper, Trends in Global Tropical Cyclone Activity: 1990–2021. One potential reason: a more La Niña-like base climate state from 1990 to 2021, which suppressed tropical cyclone activity in the North and South Pacific – the most active ocean basins for tropical cyclones. As a result, a reduction in the total number of hurricanes of all categories globally occurred (though the Atlantic saw an increase in activity).

Our other posts in this series

Bob Henson contributed to this post.