The Category 5 storm approaching Florida is the most powerful type of hurricane.
On Monday, Hurricane Milton quickly intensified from a Category 2 storm to reach the highest and most dangerous rank on what’s known as the Saffir-Simpson Hurricane Wind Scale.
The scale, which was adopted in the 1970s, categorizes hurricanes from one to five based on their maximum sustained wind speed. It is also meant to provide insight into potential damage, which can increase significantly with each category.
A hurricane is essentially a tropical cyclone that has reached wind speeds of 119 km/h or more. In addition to destructive winds, these large and rapidly rotating low-pressure storms can bring rain-induced flooding, multiple tornadoes and deadly storm surges, which is when wind pushes seawater ashore.
The term “hurricane” specifically refers to storms formed over the Atlantic Ocean and northeastern Pacific, while similar tropical cyclones are called “typhoons” in the western Pacific. According to the U.S. National Oceanic and Atmospheric Administration, any Category 3 or higher storm is considered a “major” hurricane.
This is what the Saffir-Simpson Hurricane Wind Scale categories mean:
Category 1 – 119 to 153 km/h
A tropical cyclone becomes a hurricane when it reaches sustained wind speeds of 119 km/h or more. Some damage is possible to roofs, shingles, vinyl siding and gutters on homes. Unprotected windows are also at risk of flying debris. Extensive damage to electricity lines and poles can result in dayslong power outages.
Hurricane Hazel in 1954 claimed 81 lives in Canada, largely from flooding in Toronto, where it arrived as a Category 1 storm after previously making landfall in the U.S. as a Category 4.
Category 2 – 154 to 177 km/h
Winds become extremely dangerous and capable of extensive damage. Homes can experience major roof and siding damage while trees with shallow roots will be toppled. Widespread power outages can last from days to weeks.
In 1963, Hurricane Ginny became the strongest hurricane to make landfall in Canada when it arrived in Nova Scotia as a Category 2 storm.
Category 3 – 178 to 208 km/h
Damage becomes devastating. Nearly all older mobile homes will be destroyed. Well-built houses can incur major damage, such as the removal of roof foundations. Numerous trees will be uprooted or snapped, blocking roads. Running water will also be affected in addition to electricity.
Hurricane Katrina in 2005 was one of the deadliest storms in recent U.S. history, claiming nearly 1,400 lives after it made landfall in Louisiana and Mississippi as a Category 3.
Category 4 – 209 to 251 km/h
There will be catastrophic damage. Even well-built houses can lose roofs and exterior walls. Nearly all commercial signage will be destroyed. Most trees and electricity poles will be toppled, isolating some areas and leading to lengthy power outages. Affected areas could become uninhabitable for weeks or months.
Hurricane Helene killed more than 200 people in the U.S. in September and was a Category 4 storm.
Category 5 – 252 km/h or higher
Damage is catastrophic. A high percentage of homes and almost all mobile homes will be destroyed. Most unprotected windows will be shattered in high-rise buildings. Nearly all trees and electricity poles will be knocked over, isolating some communities. Electricity and water outages could last months while impacted areas are likely to be uninhabitable for weeks or months.
Hurricane Andrew caused widespread damage in Florida in 1992 when it arrived as a Category 5 storm. As hurricanes become more intense, some scientists have even suggested creating a new Category 6.