Hurricanes are categorized by their wind speeds on the Saffir-Simpson Hurricane Scale. The scale was first developed by Herb Saffir, a structural engineer, and Bob Simpson, a meteorologist.
Hurricanes are divided into five categories based on the wind speeds they produce:
Category 1: Winds between 74 mph and 95 mph
Category 2: Winds between 96 mph and 110. mph
Category 3: Winds between 111 mph and 129 mph
Category 4: wind between 130 mph and 156 mph
Category 5: Winds of 157 mph or more.
To be considered a “major” hurricane, according to the National Hurricane Centermust reach a storm category 3 or higher.
The strength of a hurricane matters because it helps meteorologists give residents in its path an idea of what kind of damage is possible.
For example, a Category 2 hurricane can cause major roof damage to homes, breaking or uprooting shallow-rooted trees and shutting down power in an area for days to weeks.
When a hurricane reaches Category 5 strength, the center can predict “catastrophic damage will occur.” according to the Saffir-Simpson scale† Winds from a Category 5 hurricane can destroy homes, fell trees and power lines, and potentially leave an area without power for weeks to months.
Because the hurricane category scale is based only on wind speeds, a number of factors are not taken into account.
“Wind is only one of four hazards, four primary hazards, associated with a tropical cyclone,” he said dr. Michael Brennan, the acting deputy director of the National Hurricane Center, who uses the broader term for hurricane. “You can also have rain and flooding, storm surge, tornadoes, rip currents.”
Other hurricane-related hazards can arise after the storms move through an area.
For example, when an affected area loses power, many people often turn to portable generators to produce electricity. But if used incorrectly, they can lead to carbon monoxide poisoning.
Keep in mind, though, that a weak Category 1 hurricane or even a tropical storm can cause serious damage. A tropical storm can have wind speeds between 39 mph and 73 mph. If the storm gets stronger and produces winds up to 74 mph, it’s a Category 1 hurricane.
“There is very little difference — and almost an imperceptible difference — between a strong tropical storm with, say, maximum sustained winds of about 70 mph, and a Category 1 hurricane,” said Dr. Brennan. “There’s enough uncertainty out there that those differences — 1 mph or even 5 mph — don’t make a huge difference.”