How are Hurricanes Classified?

Hurricane Fran

Hurricanes are classified on the Saffir/Simpson Hurricane Damage-Potential scale. This scale assigns a number from 1 to 5 based on the potential disaster the winds and storm surge of the hurricane may cause.  The scale was developed by Herbert Saffir and Robert Simpson in 1971. It’s primarily used today for allowing disaster agencies to prepare for imminent storms and for general public awareness.

The following is a link to the National Weather Service’s Hurricane Wind Scale Summary Table. In a nutshell, the categories mean:

Category 1 – Winds: 74 to 95 mph. Storm surge: 4 to 5 feet above normal. Damage primarily to trees and unanchored mobile homes. Some coastal flooding.

Category 2 – Winds: 96 to 110 mph. Storm surge: 6 to 8 feet. Some damage to roofs, doors, windows, trees and shrubbery; flooding damage to piers.

Category 3 – Winds: 111 to 130 mph. Storm surge: 9 to 12 feet. Some structural damage; large trees blown down; flooding near shoreline and possibly inland; mobile homes destroyed.

Category 4 – Winds: 131 to 155 mph. Storm surge: 13 to 18 feet. Extensive damage to doors and windows; major damage to lower floors near shore; terrain may be flooded well inland.

Category 5 – Winds: in excess of 155 mph. Storm surge: more than 18 feet. Complete roof failure and some building failures; massive evacuation. Flooding causes major damage to lower floors of all shoreline buildings.

Source: http://www.sptimes.com/2007/04/15/Weather/How_hurricanes_are_cl.shtml.