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Hurricane Milton explodes into a powerful Category 5 storm as it heads for Florida—how rapid intensification works

Hurricane Milton went from to a in less than 24 hours as it headed across the Gulf of Mexico toward Florida.

As its wind speed increased, Milton became one of the most rapidly intensifying storms on record. And with on Oct. 7, 2024, and very low pressure, it also became one of the strongest Atlantic storms.

Less than two weeks after , this kind of storm was the last thing Florida wanted to see. Hurricane Milton was expected to make landfall as a major hurricane on Oct. 9 and had already .

So, what exactly is rapid intensification, and what does global climate change have to do with it? We and . Here's what you need to know.

What is rapid intensification?

Rapid intensification is defined by the National Weather Service as an increase in a tropical cyclone's maximum sustained wind speed of within a 24-hour period. That increase can be enough to escalate a storm from Category 1 to Category 3 on the Saffir-Simpson scale.

Milton's wind speed went to from 1 p.m. Sunday to 1 p.m. Monday, and its pressure dropped from 988 millibars to 911. Most of that intensification was .

The National Hurricane Center had been warning that Milton was likely to become a major hurricane, but this kind of rapid intensification can catch people off guard, especially when it occurs close to landfall.

Hurricane Michael did in 2018 when it rapidly intensified into a Category 5 storm just before hitting near Tyndall Air Force Base in the Florida Panhandle. In 2023, maximum wind speed increased by 100 mph in less than 24 hours before it hit Acapulco, Mexico. also rapidly intensified in 2022 before hitting just south of where Milton is projected to cross Florida.

What causes hurricanes to rapidly intensify?

Rapid intensification is difficult to forecast, but there are a few driving forces.

• Ocean heat: , particularly when they extend into deeper layers of warm water, provide the energy necessary for hurricanes to intensify. The deeper the warm water, the more energy a storm can draw upon, enhancing its strength.

• Low wind shear: Strong vertical wind shear—a rapid change in wind speed or direction with height—can disrupt a storm's organization, while low wind shear allows hurricanes to grow more rapidly. In Milton's case, the atmospheric conditions were particularly conducive to rapid intensification.
• Moisture: Higher sea surface temperatures and lower salinity increase the amount of moisture available to storms, fueling rapid intensification. Warmer waters provide the heat needed for moisture to evaporate, while lower salinity helps trap that heat near the surface. This allows more sustained heat and moisture to transfer to the storm, .
• Thunderstorm activity: Internal dynamics, such as bursts of intense thunderstorms within a cyclone's rotation, can and lead to rapid increases in strength, even when the other conditions aren't ideal.

Research has found that globally, a majority of hurricanes Category 3 and above .

How does global warming influence hurricane strength?

If it seems as though you've been hearing about rapid intensification a lot more in recent years, that's in part because .

A 2023 study investigating found an increase in the number of tropical cyclones experiencing rapid intensification over the past four decades. That includes a significant rise in the number of hurricanes that rapidly intensify multiple times during their development.

Another analysis comparing trends from 1982 to 2017 with climate model simulations found that these increases in rapidly intensifying storms, indicating a likely role of human-induced climate change.

How future climate change will affect hurricanes is an active area of research. As global temperatures and oceans continue to warm, however, . The extreme hurricanes of recent years, including Beryl in June 2024 and Helene, are already raising alarms about the intensifying impact of warming on tropical cyclone behavior.