Saffir–Simpson scale

In 1971, the scale was developed by civil engineer Herbert Saffir and meteorologist Robert Simpson, who at the time was director of the U.S. National Hurricane Center (NHC). In 1973, the scale was introduced to the general public, and saw widespread use after Neil Frank replaced Simpson at the helm of the NHC in 1974. In 1971, while conducting the study, Saffir realized there was no simple scale for describing the likely effects of a hurricane. By using subjective damage-based scales for earthquake intensity like the Modified Mercalli intensity scale or MSK-64 intensity scale and the objective numerical gradation method of the Richter scale as models, he proposed a simplified 1–5 grading scale as a guide for areas that do not have hurricane building codes. The grades were based on two main factors: objective wind gust speeds sustaining for 2–3 seconds at an elevation of 9.2 meters, and subjective levels of structural damage. Saffir gave the proposed scale to the NHC for their use, where Simpson changed the terminology from "grade" to "category", organized them by sustained wind speeds of 1 minute duration, and added storm surge height ranges, adding barometric pressure ranges later on. In 1975, the Saffir–Simpson Scale was first published publicly. In 2009, the NHC eliminated pressure and storm surge ranges from the categories, transforming it into a pure wind scale, called the Saffir–Simpson Hurricane Wind Scale (Experimental) [SSHWS]. The updated scale became operational on May 15, 2010. The scale excludes flood ranges, storm surge estimations, rainfall, and location, which means a Category 2 hurricane that hits a major city will likely do far more cumulative damage than a Category 5 hurricane that hits a rural area. Since being removed from the Saffir–Simpson hurricane wind scale, storm surge prediction and modeling is handled by computer numerical models such as ADCIRC and SLOSH. In 2012, the NHC extended the wind speed range for Category 4 by 1 mph in both directions, to 130–156 mph, with corresponding changes in the other units (113–136 kn, 209–251 km/h), instead of 131–155 mph (114–135 kn, 210–249 km/h). The NHC and the Central Pacific Hurricane Center assign tropical cyclone intensities in 5 knot increments, and then convert to mph and km/h with a similar rounding for other reports. So an intensity of 115 kn is rated Category 4, but the conversion to miles per hour (132.3 mph) would round down to 130 mph, making it appear to be a Category 3 storm. Likewise, an intensity of 135 kn (~155 mph, and thus Category 4) is 250.02 km/h, which, according to the definition used before the change would be Category 5. ==Categories==

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. The Joint Typhoon Warning Center classifies typhoons of 150 mph (240 km/h) or greater (strong Category 4 and Category 5) as super typhoons. Most weather agencies use the definition for sustained winds recommended by the World Meteorological Organization (WMO), which specifies measuring winds at a height of 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 height, and that is the definition used for this scale. The five categories are described in the following subsections, in order of increasing intensity. Example hurricanes for each category are limited to those which made landfall at their maximum achieved category on the scale. Category 1 Very dangerous winds will produce some damage Category 1 storms usually cause no significant structural damage to most well-constructed permanent structures. They can topple unanchored 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. Maria (2017), Michael (2018), Dorian (2019), Otis (2023; the only Pacific hurricane to make landfall at Category 5 intensity), and Melissa (2025). ==Criticism==

Some scientists, including Kerry Emanuel and Lakshmi Kantha, have criticized the scale as being too simplistic, namely that the scale takes into account neither the physical size of a storm nor the amount of precipitation it produces. Both of these scales are continuous, akin to the Richter scale. However, neither of these scales has been used by officials. Proposed extensions After the series of powerful storm systems of the 2005 Atlantic hurricane season, as well as after Hurricane Patricia, a few newspaper columnists and scientists brought up the suggestion of introducing Category 6. They have suggested pegging Category 6 to storms with winds greater than . Fresh calls were made for consideration of the issue after Hurricane Irma in 2017, which was the subject of a number of seemingly credible false news reports as a "Category 6" storm, partly in consequence of so many local politicians using the term. Only a few storms of this intensity have been recorded. Of the 45 hurricanes currently considered to have attained Category 5 status in the Atlantic, 20 had wind speeds at or greater. Only 10 had wind speeds at or greater (the 1935 Labor Day hurricane, Allen, Gilbert, Mitch, Rita, Wilma, Irma, Dorian, Milton, and Melissa). Of the 21 hurricanes currently considered to have attained Category 5 status in the eastern Pacific, only 5 had wind speeds at or greater (Patsy, John, Linda, Rick, and Patricia). Only 3 had wind speeds at or greater (Linda, Rick, and Patricia). Most storms which would be eligible for this category were typhoons in the western Pacific, where the scale is not officially used, most notably typhoons Tip, Halong, Mawar, and Bolaven in 1979, 2019 and 2023 (2 storms) respectively, each with sustained winds of , and typhoons Haiyan, Meranti, Goni, and Surigae in 2013, 2016, 2020 and 2021 respectively, each with sustained winds of . Occasionally, suggestions of using even higher wind speeds as the cutoff have been made. In a newspaper article published in November 2018, NOAA research scientist Jim Kossin said that the potential for more intense hurricanes was increasing as the climate warmed, and suggested that Category 6 would begin at , with a further hypothetical Category 7 beginning at . In 2024 another proposal to add "Category 6" was made, with a minimum wind speed of , with risk factors such as the effects of climate change and warming ocean temperatures part of that research. In the NHC area of responsibility, only Patricia had winds greater than . According to Robert Simpson, co-creator of the scale, there are no reasons for a Category 6 on the Saffir–Simpson scale because it is designed to measure the potential damage of a hurricane to human-made structures. Simpson explained that "... when you get up into winds in excess of you have enough damage if that extreme wind sustains itself for as much as six seconds on a building it's going to cause rupturing damages that are serious no matter how well it's engineered." Nonetheless, the counties of Broward and Miami-Dade in Florida have building codes which require that critical infrastructure buildings be able to withstand Category 5 winds. New proposed scales include those based on factors other than peak wind speed alone. One proposal involves separate scales for wind, for storm surge, and for rainfall. ==See also==