CNN

Why Hurricane Melissa turned into a supercharged monster

By CNN

Published October 29, 2025 7:21 am

CNN

By Andrew Freedman, CNN

(CNN) — The water around Jamaica had been simmering all summer. By the time Hurricane Melissa roared ashore Tuesday, that uber-warm Caribbean Sea had helped turn it into a monster: a Category 5 storm with winds reaching 185 miles an hour, tied for the strongest hurricane to strike land in the Atlantic.

Experts say it’s a visceral example of what climate change can do to the planet’s most fearsome storms — supercharging them with heat and moisture until they become almost unrecognizable from the Atlantic hurricanes of the past.

Jamaica is waking up to devastation, with severe damage to infrastructure including the electric grid, hospitals and schools. But the true extent of the damage in the hardest-hit communities may take days to uncover, as rescue workers and families struggle to reach them.

Three days before landfall, Hurricane Melissa underwent two periods of rapid intensification as it traversed ocean water that were about 2.5 degrees Fahrenheit warmer than average for this time of year.

Human-caused climate change made such hot water far more likely, according to the research group Climate Central.

And as it moved through those water, Hurricane Melissa’s maximum sustained winds doubled from 70 mph — a tropical storm — on Saturday morning to a 140 mph Category 4 hurricane just 24 hours later.

Then from Sunday afternoon through Monday afternoon its peak winds spiked again, going from 140 mph to 175 mph. It then intensified further overnight Monday into Tuesday morning during its final approach to the Jamaican coast.

This type of hurricane behavior is becoming more common. “We’ve seen a notable uptick in the rates of explosive intensification,” with winds increasing by at least 60 mph in 24 hours across most ocean basins, during the past four decades or more, said Steve Bowen, chief scientist at Gallagher Re. It’s what scientists have been predicting, he said: Hotter oceans are going to support “top-tier intensity” hurricanes.

“In short, nature continues to reaffirm the basic laws of thermodynamics.”

Kerry Emanuel, a veteran hurricane researcher at MIT, said we are now seeing evidence of greater human-caused influences on these massive storms.

“This is the third Category 5 tropical cyclone in the Atlantic this year, and the other two also went through periods of rapid intensification,” he told CNN in an email. “Taken together, this season might be said to be consistent with what we have been saying for some time,” he said, which is that: “The proportion of global tropical cyclones reaching high intensity is increasing, as is the incidence of rapidly intensifying storms.”

This season has been “fairly normal” in terms of the number of Atlantic tropical storms and hurricanes, Emanuel noted, which is also in line with studies showing that a warming world is unlikely to feature more tropical cyclones per season.

But other research indicates that as the climate warms in response to human-caused pollution, tropical storms and hurricanes are capable of dumping heavier rainfall. This is because warmer air can carry greater amounts of moisture, and warming seas also allow for the evaporation of greater amounts of water vapor into the atmosphere, giving hurricanes more energy.

Ocean temperatures are a primary driver of hurricane strength, Emanuel said. Melissa reached its so-called maximum potential intensity — a metric he devised for determining how strong a storm can theoretically get if it were able to take full advantage of such environmental drivers.

Very few storms reach this point due to inhibiting factors such as strong winds in the upper atmosphere. Melissa managed to do this despite the fact that the maximum potential intensity metric itself was above average for its location in the Caribbean at this time of year, Emanuel said. This mainly reflects the hotter ocean temperatures.

“This storm just pretty much did all of the things you wouldn’t want a storm to do,” said Daniel Swain, a climate researcher at UCLA. He said the reaching of its maximum potential intensity is especially noteworthy, and that the rapid intensification and other observed storm characteristics bear clear climate change fingerprints.

Jim Kossin, a former scientist with the National Oceanic and Atmospheric Administration (NOAA) who has conducted multiple studies on hurricanes and climate change, says connecting the dots between Hurricane Melissa and global warming, broadly, is relatively straightforward.

“The very warm water almost certainly has a human fingerprint on it and there is no question that this warm water played a key role in Melissa’s intensity and intensification rate,” he told CNN.

Other experts also pointed to the storm’s rapid intensification while located in an ocean basin with unusually hot sea surface temperatures, and hot water extending to deep depths as well, as human-caused factors that helped lead to this disaster.

However, not all aspects of the storm can be so easily attributed to climate change, including its slow movement. Despite observations of a trend toward slower-moving storms in the Atlantic and other ocean basins in recent years, the causal connection is not as well established, Kossin said.

“Maybe the most important thing to understand about hurricanes in the warming world is that not all of them will be able to take advantage of the raised ceiling from ocean warming, but some of them will, and this one did,” Swain said.

“And when we have situations like this, where it happens near or over a populated area that is susceptible to major effects, that the subsequent devastation will have been made worse, significantly worse, by climate change.”