Good Question: What Do Hurricane Category Numbers Mean?

MINNEAPOLIS (WCCO) — Hurricane Matthew is expected to make landfall Friday morning in Florida as a Category-4 storm.

It is expected to become a Category 2 by Saturday as it moves up the coast.

So, what do those category numbers mean?

“It’s similar to how we rate tornados,” says Shawn DeVinny, a meteorologist with the National Weather Service in Chanhassen. “All it’s telling you is what the maximum sustained winds are with the hurricane.”

(credit: CBS)

(credit: CBS)

Only three hurricanes to make landfall in the United States in the past 46 years have been a Category 4 or 5: Andrew (1992), Charley (2004) and Hugo (1989).

“We can tell with a Category 4 such as this there’s going to be devastation for structures and trees, and power outages will be widespread and long-lasting,” DeVinny said.

The numbering system — called the Saffir-Simpson scale — was created in 1971. It was developed by and named after a meteorologist and a wind engineer.

DeVinny says the scale is considered the best way to measure the strength of a hurricane because wind speed can tell people the most immediate life-threatening impact.

“It’s like a strong tornado similarly, but in a much more wide area,” DeVinny said.

The category numbers increase in terms of sustained wind-speed severity:

  • Category 1: 74 to 95 miles per hour
  • Category 2: 96 to 110 miles per hour
  • Category 3: 111 to 129 miles per hour
  • Category 4: 130 to 156 miles per hour
  • Category 5: 157 miles per hour or more
  • The costliest hurricanes to hit the U.S. are Katrina (2005), Andrew (1992), Ike (2008), Wilma (2005) and Ivan (2004). They were a mixture of Categories 2, 3, 4 and 5.

    “You’re comparing a wind speed higher in this case, other hurricanes might be more costly in terms of dollars if there’s a lot worse flooding with those,” DeVinny said.

    Superstorm Sandy was not technically a hurricane.

    More from Heather Brown

    One Comment

    1. Rob says:

      Crazy Hillary is trying to blame the hurricane on Global Warming!

      What a nut. There haven’t been any significant hurricanes in ten years. If there really WAS global warming, it should be obvious is is reducing hurricanes.

      Her lies are endless.

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