Saffir-Simpson Hurricane Scale

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Category 1, Category 2 and Category 4 redirect here. For other meanings of Category 4, see Category 4 (disambiguation).

The Saffir-Simpson Hurricane Scale is a scale classifying hurricanes by the intensity of their sustained winds, developed in 1969 by civil engineer Herbert Saffir and National Hurricane Center director Bob Simpson. Classifications are used to gauge the likely damage and flooding a hurricane will cause upon landfall. The Saffir-Simpson Hurricane Scale is used only to describe hurricanes forming in the Atlantic Ocean and northern Pacific Ocean east of the International Date Line. Other areas use their own classification schemes, such as cyclones and typhoons.

The Australian Bureau of Meteorology uses a 1-5 scale called tropical cyclone severity categories. Unlike the Saffir-Simpson Scale, severity categories are based on strongest wind gusts and not sustained winds. Severity categories are scaled somewhat lower than the Saffir-Simpson Scale, with a severity category 2 tropical cyclone being roughly equivalent to a Saffir-Simpson category 1 hurricane.

The initial scale was developed by Saffir while on commission from the United Nations to study low-cost housing in hurricane-prone areas. While performing the study, Saffir realized there was no simple scale for describing the likely effects of a hurricane. Knowing the utility of the Richter magnitude scale in describing earthquakes, he devised a 1–5 scale based on wind speed that showed expected damage to structures. Saffir gave the scale to the NHC, and Simpson added in the effects of storm surge and flooding. It does not take into account rainfall or location, which means a Category 3 hurricane that hits a major city will likely do far more damage than a Category 5 hurricane that hits a rural area.

The five categories are, in order of increasing intensity:

Category 1 Sustained winds 33–42 m/s 74–95 mph 64–82 kt 119–153 km/h
Storm surge 4–5 ft 1.2–1.5 m
Central pressure 28.94 inHg 980 mbar
Potential damage No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Also, some coastal flooding and minor pier damage.
Example storms Hurricane AgnesHurricane DannyHurricane DianeHurricane Gaston
Category 2 Sustained winds 43–49 m/s 96–110 mph 83–95 kt 154–177 km/h
Storm surge 6–8 ft 1.8–2.4 m
Central Pressure 28.50–28.91 inHg 965–979 mbar
Potential damage Some roofing material, door, and window damage. Considerable damage to vegetation, mobile homes, etc. Flooding damages piers and small craft in unprotected boats may break their moorings.
Example storms Hurricane BobHurricane BonnieHurricane DoraHurricane FrancesHurricane Juan
Category 3 Sustained winds 50–58 m/s 111–130 mph 96–113 kt 178–209 km/h
Storm surge 9–12 ft 2.7–3.7 m
Central pressure 27.91–28.47 inHg 945–964 mbar
Potential damage Some structural damage to small residences and utility buildings, with a minor amount of curtainwall failures. Mobile homes are destroyed. Flooding near the coast destroys smaller structures with larger structures damaged by floating debris. Terrain may be flooded well inland.
Example storms Hurricane FranGreat New England Hurricane of 1938Hurricane IsidoreHurricane JeanneHurricane OpalHurricane Rita
Category 4 Sustained winds 59–69 m/s 131–155 mph 114–135 kt 210–249 km/h
Storm surge 13–18 ft 4.0–5.5 m
Central pressure 27.17–27.88 inHg 920–944 mbar
Potential damage More extensive curtainwall failures with some complete roof structure failure on small residences. Major erosion of beach areas. Terrain may be flooded well inland.
Example storms Hurricane CharleyHurricane DonnaGalveston Hurricane of 1900Hurricane HugoHurricane IrisHurricane Wilma
Category 5 Sustained winds ≥70 m/s ≥156 mph ≥136 kt ≥250 km/h
Storm surge ≥19 ft ≥5.5 m
Central pressure <27.17 inHg <920 mbar
Potential damage Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. Flooding causes major damage to lower floors of all structures near the shoreline. Massive evacuation of residential areas may be required.
Example storms Hurricane AndrewHurricane CamilleHurricane EdithHurricane GilbertLabor Day Hurricane of 1935

All wind speeds are based on a one-minute average. Central pressure values are approximate. Intensity of example hurricanes is at time of landfall, not peak intensity (if it was stronger in the open water).

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