The Saffir–Simpson hurricane wind scale (SSHWS), formerly the Saffir–Simpson hurricane scale (SSHS), classifies hurricanes – Western Hemisphere tropical cyclones – that exceed the intensities of tropical depressions and tropical storms – into five categories distinguished by the intensities of their sustained winds.
(for 1-minute maximum sustained winds)
|Five||≥ 70 m/s||≥ 137 kn||≥ 157 mph||≥ 252 km/h|
|Four||58–70 m/s||113–136 kn||130–156 mph||209–251 km/h|
|Three||50–58 m/s||96–112 kn||111–129 mph||178–208 km/h|
|Two||43–49 m/s||83–95 kn||96–110 mph||154–177 km/h|
|One||33–42 m/s||64–82 kn||74–95 mph||119–153 km/h|
|Tropical storm||18–32 m/s||34–63 kn||39–73 mph||63–118 km/h|
|Tropical depression||≤ 17 m/s||≤ 33 kn||≤ 38 mph||≤ 62 km/h|
To be classified as a hurricane, a tropical cyclone must have one-minute-average maximum sustained winds at 10 m above the surface of at least 74 mph (Category 1). The highest classification in the scale, Category 5, consists of storms with sustained winds of at least 157 mph. See the table to the right for all five categories with wind speeds in various units. The classifications can provide some indication of the potential damage and flooding a hurricane will cause upon landfall.
The Saffir–Simpson hurricane wind scale is based on the highest wind speed averaged over a one-minute interval 10 m above the surface. Although the scale shows wind speeds in continuous speed ranges, the National Hurricane Center and the Central Pacific Hurricane Center assign tropical cyclone intensities in 5-knot (kt) increments (e.g., 100, 105, 100, 115 kt, etc.) because of the inherent uncertainty in estimating the strength of tropical cyclones. Wind speeds in knots are then converted to other units and rounded to the nearest 5 mph or 5 km/h.
The Saffir–Simpson hurricane wind scale is used officially only to describe hurricanes that form in the Atlantic Ocean and northern Pacific Ocean east of the International Date Line. Other areas use different scales to label these storms, which are called cyclones or typhoons, depending on the area. These areas (except the JTWC) use three-minute or ten-minute averaged winds to determine the maximum sustained wind speed, creating an important difference which frustrates direct comparison between maximum wind speeds of storms measured using the Saffir–Simpson hurricane wind scale (usually 14% more intense) and those measured using a ten-minute interval (usually 12% less intense).
There is some criticism of the SSHWS for not accounting for rain, storm surge, and other important factors, but SSHWS defenders say that part of the goal of SSHWS is to be straightforward and simple to understand.
The scale separates hurricanes into five different categories based on wind. The U.S. National Hurricane Center classifies hurricanes of Category 3 and above as major hurricanes, and the Joint Typhoon Warning Center classifies typhoons of 150 mph or greater (strong Category 4 and Category 5) as super typhoons (although all tropical cyclones can be very dangerous). Most weather agencies use the definition for sustained winds recommended by the World Meteorological Organization (WMO), which specifies measuring winds at a height of 33 ft (10.1 m) for 10 minutes, and then taking the average. By contrast, the U.S. National Weather Service, Central Pacific Hurricane Center and the Joint Typhoon Warning Center define sustained winds as average winds over a period of one minute, measured at the same 33 ft (10.1 m) height, and that is the definition used for this scale.
The scale is roughly logarithmic in wind speed.
The five categories are described in the following subsections, in order of increasing intensity. Intensity of example hurricanes is from both the time of landfall and the maximum intensity.
|Sustained winds||Most recent landfall|
|33–42 m/s |
|mobile homes, as well as uproot or snap weak trees. Poorly attached roof shingles or tiles can blow off. Coastal flooding and pier damage are often associated with Category 1 storms. Power outages are typically widespread to extensive, sometimes lasting several days. Even though it is the least intense type of hurricane, they can still produce widespread damage and can be life-threatening storms.|
Hurricanes that peaked at Category 1 intensity and made landfall at that intensity include: Agnes (1972), Juan (1985), Ismael (1995), Danny (1997), Claudette (2003), Gaston (2004), Stan (2005), Humberto (2007), Isaac (2012), Manuel (2013), Earl (2016), Hermine (2016), Nate (2017), Barry (2019), Lorena (2019), Hanna (2020), Isaias (2020), Nana (2020), and Gamma (2020).