Hurricane categories are rated by wind speed using the Saffir-Simpson Hurricane Wind Scale. This is hurricane-specific and does not factor in the impact of hazards like storm surges and rainfall flooding. The Saffir-Simpson Hurricane Wind Scale is an efficient measure of property damage caused by hurricane winds.
Origin of the Scale
The scale was created in 1969 at the request of the World Meteorological Organization by two meteorologists, one of whom was a director of the National Hurricane Centre. The goal was to clearly classify hurricanes by wind speed, to determine potential population and infrastructure damage. The scale only applies to certain basins, one of which is the Atlantic and the wind speed is tested over a period of a minute using the scale to categorize a hurricane.
Evolution of the Scale
Weather patterns have significantly shifted since 1969, and climate change is fueling the strong hurricanes and tropical storms being formed in the Atlantic. The 2005 hurricane season which saw the likes of Hurricane Katrina in New Orleans and Tropical Storm Ivan in Grenada was pivotal in raising questions about the classification system. Though there were suggestions to have a sixth category, minor changes were made by the NHC to categories 3, 4, and 5.
Here is a breakdown of the hurricane scale from the National Hurricane Centre/ National Oceanic and Atmospheric Administration.
|Category||Sustained Winds||Type of Damage|
|Very dangerous winds will produce some damage: Well-constructed homes could have damage to the roof and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.|
|Extremely dangerous winds will cause extensive damage: Well-constructed homes could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks.|
|Devastating damage will occur: Well-built homes may incur major damage or removal of roof decking. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.|
|Catastrophic damage will occur: Well-built homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months|
|157 mph or higher
137 kt or higher
|Catastrophic damage will occur: A high percentage of homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas|