The Saffir-Simpson Hurricane Scale: What Is It and What Do the Categories Mean?
The Saffir-Simpson Hurricane Scale was developed in 1971 by engineer Herbert Saffir and metereologist Bob Simpson. It was introduced to the public in 1973 and gained widespread acceptance starting in 1974. Today it is the classification system used to categorize Western Hemisphere tropical cyclones that exceed the strength of tropical depressions and tropical storms.
Saffir initially developed the scale in 1969 while working for the United Nations. He was commissioned to study low-income housing and realized there was no way to measure hurricanes. Using the Richter Scale as a model he developed a similar 1-5 scale as a way to describe the likely effects of a hurricane’s winds on structures such as buildings. Saffir gave his scale to the National Hurricane Center where Simpson added the effects of storm surge and flooding.
The scale has some flaws though and the National Hurricane Center (NHC) has now introduced the Saffir-Simpson Hurricane Wind Scale which categorizes hurricanes based on wind effects alone. The NHC has done this because several hurricanes have caused far greater or lesser damage than their category indicated they would. For example, Hurricane Katrina was a category three when it made landfall but because of New Orleans’ low-lying location and dense population, Katrina caused much more damage than expected. The main problem with the Saffir-Simpson Hurricane Scale has been that it does not take location into consideration so the scale does not predict that a category two hurricane that strikes a major city will cause far more damage than a category five hurricane that strikes a rural area. The Saffir-Simpson Hurricane Scale and Hurricane Wind Scale are divided into five categories.
Saffir-Simpson Hurricane Scale Categories
A Category One hurricane has sustained winds of 74 to 95 miles per hour. A Category One storm usually does not cause significant structural damage. However, it can topple unanchored mobile homes or destroy older ones. Roof shingles can blow off and people or animals that are outside can be injured or killed by flying debris. Flooding can also cause damage, especially when the storm moves very slowly.
A Category Two hurricane has sustained winds of 96 to 110 miles per hour. A Category Two storm can lift a house and damage poorly built doors and windows. Landscaping, signs and piers can also be damaged. Mobile homes, whether anchored or not, can be severely damage and older ones often receive significant structural damage.
A Category Three hurricane has sustained winds of 111 to 129 miles per hour. A Category Three or higher storm is classified as a major hurricane. In this middle range of classification, a storm can cause structural damage to small buildings. Mobile homes are destroyed. Gable roofs are torn off, and flooding in coastal areas can cause significant damage, especially to smaller buildings. Recent Category Three hurricanes were Epsilon in 2020 (Bermuda), Humberto in 2019 (the Caribbean), and Ophelia in 2017 (Europe).
A Category Four hurricane has sustained winds of 130 to 156 miles per hour. A storm in this category can cause complete structural failure of roofs, flooding far inland, complete destruction of mobile homes and significant beach erosion. Notable Category Four hurricanes were the 1900 Galveston Hurricane, Iris in 2001 and Charley in 2004. The 2020 hurricane season witnessed a record-breaking three Category Four hurricanes - Laura and Delta struck Louisiana and Teddy passed close to Bermuda on the way to Canada.
A Category Five hurricane has sustained winds over 156 miles per hour. Category Five storms cause complete destruction of mobile homes and many wood frame structures as well as complete roof failure on many buildings. Vegetation is destroyed and trees are completely uprooted. Windows and doors fail, one of the reasons for roof failures and why hurricane resistant windows are mandatory in most coastal areas. Flooding causes major damage in coastal areas. Waterfront homes are flattened. Category Five storms rarely make landfall at that intensity. Some of the ones that have are Andrew in 1992 (Florida), Irma in 2017 (the Caribbean), Maria in 2017 (the Caribbean), Michael in 2018 (Florida), and Dorian in 2019 (Bahamas).
Following the extraordinary 2005 hurricane season, some newspaper columnists and scientists suggested adding a Category Six which would include storms with wind speeds greater than 174 or 180 miles per hour. The idea was not widely accepted for several reasons, one being that storms of that intensity are extremely rare. Robert Simpson was one of the detractors of the suggestion, saying that if the wind speed is over 155 miles per hour the damage to a building will be “serious no matter how well it's engineered". In recent years, though, the idea has been discussed again, especially has stronger and deadlier hurricanes become more common.
The Saffir-Simpson Hurricane Scale has drawn criticism for its simplicity and because it does not take into consideration many factors that affect how damaging a hurricane can be. Some scientists have proposed using other classification scales such as Hurricane Intensity Index, which is based on the pressure caused by a hurricane’s winds, and the Hurricane Hazard Index, which is based on surface wind speeds and the radius of maximum winds within a storm. Like the idea of adding a sixth category, the use of other scales has not gained wide popularity and none are currently in use by officials. Until such time as another classification system is either introduced or used, the Saffir-Simpson Hurricane Scale and Hurricane Wind Scales will be the official way of classifying Atlantic hurricanes.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2010 Cristina Vanthul