Saffir–Simpson scale

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.

Saffir–Simpson scale
Category Wind speeds
(for 1-minute maximum sustained winds)
m/s knots (kn) mph km/h
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  
Related classifications
(for 1-minute maximum sustained winds)
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 maximum sustained winds of at least 74 mph (33 m/s; 64 kn; 119 km/h) (Category 1). The highest classification in the scale, Category 5, consists of storms with sustained winds over 156 mph (70 m/s; 136 kn; 251 km/h). The classifications can provide some indication of the potential damage and flooding a hurricane will cause upon landfall.

Officially, the Saffir–Simpson hurricane wind scale is based on the highest average wind over a one-minute time span and used 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 winds—which is an important difference and makes direct comparison with storms scaled with the Saffir–Simpson method difficult.

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 was developed in 1971 by civil engineer Herbert Saffir and meteorologist Robert Simpson, who at the time was director of the U.S. National Hurricane Center (NHC).[1] The scale was introduced to the general public in 1973,[2] and saw widespread use after Neil Frank replaced Simpson at the helm of the NHC in 1974.[3]

The initial scale was developed by Herbert Saffir, a structural engineer, who in 1969 went on commission for the United Nations to study low-cost housing in hurricane-prone areas.[4] While conducting the study, Saffir realized there was no simple scale for describing the likely effects of a hurricane. Mirroring the utility of the Richter magnitude scale for 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 the effects of storm surge and flooding.

In 2009, the NHC made moves to eliminate pressure and storm surge ranges from the categories, transforming it into a pure wind scale, called the Saffir–Simpson Hurricane Wind Scale (Experimental) [SSHWS].[5] The new scale became operational on May 15, 2010.[6] 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.[7] The agency cited various hurricanes as reasons for removing the "scientifically inaccurate" information, including Hurricane Katrina (2005) and Hurricane Ike (2008), which both had stronger than estimated storm surges, and Hurricane Charley (2004), which had weaker than estimated storm surge.[8] Since being removed from the Saffir–Simpson hurricane wind scale, storm surge predicting and modeling is now handled with the use of computer numerical models such as ADCIRC and SLOSH.

In 2012, the NHC expanded the windspeed 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. To resolve these issues, the NHC had been obliged to incorrectly report storms with wind speeds of 115 kn as 135 mph, and 135 kn as 245 km/h. The change in definition allows storms of 115 kn to be correctly rounded down to 130 mph, and storms of 135 kn to be correctly reported as 250 km/h, and still qualify as Category 4. Since the NHC had previously rounded incorrectly to keep storms in Category 4 in each unit of measure, the change does not affect the classification of storms from previous years.[5] The new scale became operational on May 15, 2012.[9]


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,[10][11] and that is the definition used for this scale. Intensity of example hurricanes is from both the time of landfall and the maximum intensity.

The scale is roughly logarithmic in wind speed, and the top wind speed for Category “c” (c = 1 ... 4; there is no upper limit for category 5) can be expressed as 83×10(​c15) miles per hour rounded to the nearest multiple of 5 – except that after the change mentioned above, Category 4 is now widened by 1 mph in each direction and that the calculated value for Category 2 (c = 2) is rounded down from 112.8 mph to 110 mph.

The five categories are described in the following subsections, in order of increasing intensity.[12]

Category 1

Category 1
Sustained winds Most recent
33–42 m/s
64–82 kn
119–153 km/h
74–95 mph
Nate 2017-10-07 1848ZNate in 2017 approaching Louisiana.

Very dangerous winds will produce some damage

Category 1 storms usually cause no significant structural damage to most well-constructed permanent structures; however, 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.[5]

Hurricanes that peaked at Category 1 intensity, and made landfall at that intensity include: Flossy (1956), Gladys (1968), Beth (1971), Agnes (1972), Juan (1985), Ismael (1995), Claudette (2003), Gaston (2004), Stan (2005), Humberto (2007), Isaac (2012), Manuel (2013), Earl (2016), Hermine (2016), Newton (2016), Franklin (2017), and Nate (2017).

Category 2

Category 2
Sustained winds Most recent
43–49 m/s
83–95 kn
154–177 km/h
96–110 mph
Arthur 2014-07-03 2130Z
Arthur in 2014 approaching North Carolina.

Extremely dangerous winds will cause extensive damage

Storms of Category 2 intensity often damage roofing material (sometimes exposing the roof) and inflict damage upon poorly constructed doors and windows. Poorly constructed signs and piers can receive considerable damage and many trees are uprooted or snapped. Mobile homes, whether anchored or not, are typically damaged and sometimes destroyed, and many manufactured homes also suffer structural damage. Small craft in unprotected anchorages may break their moorings. Extensive to near-total power outages and scattered loss of potable water are likely, possibly lasting many days.[5]

Hurricanes that peaked at Category 2 intensity, and made landfall at that intensity include: Able (1952), Alice (1954), Fifi (1974), Diana (1990), Calvin (1993), Gert (1993), Rosa (1994), Erin (1995), Alma (1996), Juan (2003), Catarina (2004), Alex (2010), Richard (2010), Tomas (2010), Carlotta (2012), Ernesto (2012), and Arthur (2014).

Category 3

Category 3
Sustained winds Most recent
50–58 m/s
96–112 kn
178–208 km/h
111–129 mph
Otto 2016-11-24 1605Z
Otto in 2016 at its Nicaragua landfall.

Devastating damage will occur

Tropical cyclones of Category 3 and higher are described as major hurricanes in the Atlantic or Eastern Pacific basins. These storms can cause some structural damage to small residences and utility buildings, particularly those of wood frame or manufactured materials with minor curtain wall failures. Buildings that lack a solid foundation, such as mobile homes, are usually destroyed, and gable-end roofs are peeled off. Manufactured homes usually sustain severe and irreparable damage. Flooding near the coast destroys smaller structures, while larger structures are struck by floating debris. A large number of trees are uprooted or snapped, isolating many areas. Additionally, terrain may be flooded well inland. Near-total to total power loss is likely for up to several weeks and water will likely also be lost or contaminated.[5]

Hurricanes that peaked at Category 3 intensity, and made landfall at that intensity include: Easy (1950), Carol (1954), Hilda (1955), Isbell (1964), Celia (1970), Ella (1970), Eloise (1975), Olivia (1975), Alicia (1983), Elena (1985), Roxanne (1995), Fran (1996), Isidore (2002), Jeanne (2004), Lane (2006), Karl (2010), and Otto (2016).

Category 4

Category 4
Sustained winds Most recent
58–70 m/s
113–136 kn
209–251 km/h
130–156 mph
Harvey 2017-08-25 2231Z Harvey in 2017 nearing landfall in Texas.

Catastrophic damage will occur

Category 4 hurricanes tend to produce more extensive curtainwall failures, with some complete structural failure on small residences. Heavy, irreparable damage and near complete destruction of gas station canopies and other wide span overhang type structures are common. Mobile and manufactured homes are often flattened. Most trees, except for the heartiest, are uprooted or snapped, isolating many areas. These storms cause extensive beach erosion, while terrain may be flooded far inland. Total and long-lived electrical and water losses are to be expected, possibly for many weeks.[5]

The 1900 Galveston hurricane, the deadliest natural disaster to hit the United States, peaked at an intensity that corresponds to a modern-day Category 4 storm. Other examples of storms that peaked at Category 4 intensity, and made landfall at that intensity include: Hazel (1954), Gracie (1959), Donna (1960), Flora (1963), Cleo (1964), Betsy (1965), Frederic (1979), Joan (1988), Iniki (1992), Luis (1995), Iris (2001), Charley (2004), Dennis (2005), Gustav (2008), Ike (2008), Joaquin (2015), and Harvey (2017).

Category 5

Category 5
Sustained winds Most recent
≥ 70 m/s
≥ 137 kn
≥ 252 km/h
≥ 157 mph
Michael 2018-10-10 1715Z cropped Michael in 2018 during its Florida landfall.

Catastrophic damage will occur

Category 5 is the highest category of the Saffir–Simpson scale. These storms cause complete roof failure on many residences and industrial buildings, and some complete building failures with small utility buildings blown over or away. Collapse of many wide-span roofs and walls, especially those with no interior supports, is common. Very heavy and irreparable damage to many wood frame structures and total destruction to mobile/manufactured homes is prevalent. Only a few types of structures are capable of surviving intact, and only if located at least 3 to 5 miles (5 to 8 km) inland. They include office, condominium and apartment buildings and hotels that are of solid concrete or steel frame construction, multi-story concrete parking garages, and residences that are made of either reinforced brick or concrete/cement block and have hipped roofs with slopes of no less than 35 degrees from horizontal and no overhangs of any kind, and if the windows are either made of hurricane-resistant safety glass or covered with shutters. Unless all of these requirements are met, the absolute destruction of a structure is certain.[5]

The storm's flooding causes major damage to the lower floors of all structures near the shoreline, and many coastal structures can be completely flattened or washed away by the storm surge. Virtually all trees are uprooted or snapped and some may be debarked, isolating most affected communities. Massive evacuation of residential areas may be required if the hurricane threatens populated areas. Total and extremely long-lived power outages and water losses are to be expected, possibly for up to several months.[5]

Historical examples of storms that made landfall at Category 5 status include: "Cuba" (1924), "Okeechobee" (1928), "Bahamas" (1932), "Cuba–Brownsville" (1933), "Labor Day" (1935), Janet (1955), Camille (1969), Edith (1971), Anita (1977), David (1979), Gilbert (1988), Andrew (1992), Dean (2007), Felix (2007), Irma (2017),[13] Maria (2017),[14] and Michael (2018).[15] No Category 5 hurricane is known to have made landfall at that strength in the eastern Pacific basin.


Some scientists, including Kerry Emanuel and Lakshmi Kantha, have criticized the scale as being simplistic, indicating that the scale takes into account neither the physical size of a storm nor the amount of precipitation it produces.[7] Additionally, they and others point out that the Saffir–Simpson scale, unlike the Richter scale used to measure earthquakes, is not continuous, and is quantized into a small number of categories. Proposed replacement classifications include the Hurricane Intensity Index, which is based on the dynamic pressure caused by a storm's winds, and the Hurricane Hazard Index, which is based on surface wind speeds, the radius of maximum winds of the storm, and its translational velocity.[16][17] Both of these scales are continuous, akin to the Richter scale;[18] however, neither of these scales have been used by officials.

"Category 6"

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, and they have suggested pegging Category 6 to storms with winds greater than 174 or 180 mph (78 or 80 m/s; 151 or 156 kn; 280 or 290 km/h).[7][19] Fresh calls were made for consideration of the issue after Hurricane Irma in 2017,[20] which was the subject of a number of seemingly credible false news reports as a "Category 6" storm,[21] partly in consequence of so many local politicians using the term. Only a few storms of this intensity have been recorded. Of the 33 hurricanes currently considered to have attained Category 5 status in the Atlantic, 18 had wind speeds at 175 mph (78 m/s; 152 kn; 282 km/h) or greater and only seven had wind speeds at 180 mph (80 m/s; 160 kn; 290 km/h) or greater (the 1935 Labor Day hurricane, Allen, Gilbert, Mitch, Rita, Wilma, and Irma). Of the 18 hurricanes currently considered to have attained Category 5 status in the eastern Pacific, only five had wind speeds at 175 mph (78 m/s; 152 kn; 282 km/h) or greater (Patsy, John, Linda, Rick, and Patricia), and only three had wind speeds at 180 mph (80 m/s; 160 kn; 290 km/h) or greater (Linda, Rick, and Patricia). Most storms which would be eligible for this category were typhoons in the western Pacific, most notably Typhoon Tip in 1979, with sustained winds of 190 mph (310 km/h),[22] and typhoons Haiyan and Meranti in 2013 and 2016, respectively, each with sustained winds of 195 mph (314 km/h). 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 195 mph (87 m/s; 169 kn; 314 km/h), with a further hypothetical Category 7 beginning at 230 mph (100 m/s; 200 kn; 370 km/h).[23]

According to Robert Simpson, 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 stated that "... when you get up into winds in excess of 155 mph (249 km/h) 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."[3] Nonetheless, the counties of Broward and Miami-Dade in Florida have building codes that require that critical infrastructure buildings be able to withstand Category 5 winds.[24]

See also


  1. ^ Williams, Jack (May 17, 2005). "Hurricane scale invented to communicate storm danger". USA Today. Retrieved February 25, 2007.
  2. ^ Staff writer (May 9, 1973). "'73, Hurricanes to be Graded". Associated Press. Archived from the original on May 19, 2016. Retrieved December 8, 2007.
  3. ^ a b Debi Iacovelli (July 2001). "The Saffir/Simpson Hurricane Scale: An Interview with Dr. Robert Simpson". Sun-Sentinel. Fort Lauderdale, FL. Retrieved September 10, 2006.
  4. ^ Press Writer (August 23, 2001). "Hurricanes shaped life of scale inventor". Archived from the original on April 17, 2016. Retrieved March 20, 2016.
  5. ^ a b c d e f g h The Saffir–Simpson Hurricane Wind Scale National Hurricane Center. Accessed 2009-05-15.
  6. ^ National Hurricane Operations Plan Archived July 8, 2011, at the Wayback Machine, NOAA. Accessed July 3, 2010.
  7. ^ a b c Ker Than (October 20, 2005). "Wilma's Rage Suggests New Hurricane Categories Needed". LiveScience. Retrieved October 20, 2005.
  8. ^ "Experimental Saffir–Simpson Hurricane Wind Scale" (PDF). National Hurricane Center. 2009.
  9. ^ Public Information Statement, NOAA. Accessed March 9, 2012.
  10. ^ Tropical Cyclone Weather Services Program (June 1, 2006). "Tropical cyclone definitions" (PDF). National Weather Service. Retrieved November 30, 2006.
  11. ^ Federal Emergency Management Agency (2004). "Hurricane Glossary of Terms". Archived from the original on December 14, 2005. Retrieved March 24, 2006. Accessed through the Wayback Machine.
  12. ^ "Name That Hurricane: Famous Examples of the 5 Hurricane Categories". Live Science. Retrieved September 11, 2017.
  13. ^ "Famous Hurricanes of the 20th and 21st Century in the United States" (PDF).
  14. ^ Blake, Eric (September 20, 2017). Hurricane Maria Tropical Cyclone Update (Report). Miami, Florida: National Hurricane Center. Retrieved September 20, 2017.
  15. ^ John L. Beven II; Robbie Berg; Andrew Hagen (April 19, 2019). Tropical Cyclone Report: Hurricane Michael (PDF) (Technical report). National Hurricane Center. Retrieved April 19, 2019.
  16. ^ Kantha, L. (January 2006). "Time to Replace the Saffir–Simpson Hurricane Scale?" (PDF). Eos. 87 (1): 3, 6. Bibcode:2006EOSTr..87....3K. doi:10.1029/2006eo010003. Retrieved December 8, 2007.
  17. ^ Kantha, Lakshmi (February 2008). "Tropical Cyclone Destructive Potential by Integrated Kinetic Energy". Bulletin of the American Meteorological Society. 89 (2): 219–221. Bibcode:2008BAMS...89..219K. CiteSeerX doi:10.1175/BAMS-89-2-219.
  18. ^ Benfield Hazard Research Centre (2006). "Atmospheric Hazards". Hazard & Risk Science Review 2006. University College London. Archived from the original on 7 August 2008. Retrieved 8 December 2007.
  19. ^ Bill Blakemore (May 21, 2006). "Category 6 Hurricanes? They've Happened: Global Warming Winds Up Hurricane Scientists as NOAA Issues Its Atlantic Hurricane Predictions for Summer 2006". ABC News. Retrieved September 10, 2006.
  20. ^ "Climate scientists mull Category 6 storm classification, report says". ABC News. February 22, 2018.
  21. ^ "Hurricane Irma: Will Irma become world's first CATEGORY 6 hurricane with 200mph winds?". Daily Express. September 5, 2017.
  22. ^ Debi Iacovelli and Tim Vasquez (1998). "Supertyphoon Tip: Shattering all records" (PDF). Monthly Weather Log. National Oceanic and Atmospheric Administration. Retrieved September 19, 2010.
  23. ^ "Category 6? Scientists warn hurricanes could keep getting stronger". Tampa Bay Times. November 30, 2018. Retrieved November 30, 2018.
  24. ^ Jennifer Kay (September 2017). "Irma could test strength of Florida's strict building codes". The Washington Post. Washington, DC. Retrieved September 16, 2017.

External links

1898 Georgia hurricane

The 1898 Georgia hurricane was a major hurricane that hit the U.S. state of Georgia, as well as the strongest on record in the state. It was first observed on September 29, although modern researchers estimated that it developed four days earlier to the east of the Lesser Antilles. The hurricane maintained a general northwest track throughout its duration, and it reached peak winds of 135 mph (215 km/h) on October 2. That day, it made landfall on Cumberland Island in Camden County, Georgia, causing record storm surge flooding. The hurricane caused heavy damage throughout the region, and killed at least 179 people. Impact was most severe in Brunswick, where a 16 ft (4.9 m) storm surge was recorded. Overall damage was estimated at $1.5 million (1898 USD), most of which occurred in Georgia. In extreme northeastern Florida, strong winds nearly destroyed the city of Fernandina, while light crop damage was reported in southern South Carolina. After moving ashore, the hurricane quickly weakened and traversed much of North America; it continued northwestward until reaching the Ohio Valley and turning northeastward, and it was last observed on October 6 near Newfoundland.

1924 Cuba hurricane

The 1924 Cuba hurricane is the earliest officially classified Category 5 Atlantic hurricane on the Saffir–Simpson scale (SSHS), and one of two hurricanes to make landfall on Cuba at Category 5 intensity, the other being Hurricane Irma in 2017 – both are also tied for the strongest Cuban landfall in terms of maximum sustained winds. The hurricane formed on October 14 in the western Caribbean, slowly organizing as it tracked northwestward. By October 16, the storm attained hurricane status to the east of the Yucatán Peninsula, and subsequently executed a small counterclockwise loop. On October 18, the hurricane began undergoing rapid deepening, and the on next day it, reached an estimated peak intensity of 165 mph (270 km/h). Shortly thereafter, it struck extreme western Cuba at peak intensity, becoming the strongest hurricane on record to hit the country. Later the hurricane weakened greatly, striking southwestern Florida with winds of 90 mph (150 km/h) in a sparsely populated region. While crossing the state it weakened to tropical storm status, and after accelerating east-northeastward, it was absorbed by a cold front on October 23, to the south of Bermuda.

Across the western Caribbean Sea, the developing storm produced heavy rainfall and increased winds. Strong winds in western Cuba caused severe damage, with two small towns nearly destroyed. About 90 people were killed in the country, all in Pinar del Río Province. Later, the hurricane brought heavy rainfall to southern Florida, which caused flooding and crop damage. Damage was light in the state, and there were no casualties.

1933 Outer Banks hurricane

The 1933 Outer Banks hurricane lashed portions of the North Carolina and Virginia coasts less than a month after another hurricane hit the general area. The twelfth tropical storm and sixth hurricane of the 1933 Atlantic hurricane season, it formed by September 8 to the east of the Lesser Antilles. It moved generally to the north-northwest and strengthened quickly to peak winds of 140 mph (220 km/h) on September 12. This made it a major hurricane and a Category 4 on the Saffir-Simpson scale. The hurricane remained at or near that intensity for several days while tracking to the northwest. It weakened approaching the southeastern United States, and on September 16 passed just east of Cape Hatteras, North Carolina with winds of about 100 mph (160 km/h). Turning to the northeast, the hurricane became extratropical on September 18 before moving across Atlantic Canada, eventually dissipating four days later.

The threat of the hurricane prompted widespread tropical cyclone warnings and watches along the eastern United States and prompted some people to evacuate. Damage was heaviest in southeastern North Carolina near New Bern, where the combination of high tides and swollen rivers flooded much of the town. Across North Carolina, the hurricane caused power outages, washed out roads, and damaged crops. Several houses were damaged, leaving about 1,000 people homeless. Damage was estimated at $4.5 million, and there were 21 deaths in the state, mostly from drowning. Hurricane-force winds extended into southeastern Virginia, where there were two deaths. High tides isolated a lighthouse near Norfolk and covered several roads. Farther north, two people on a small boat were left missing in Maine, and another person was presumed killed when his boat sank in Nova Scotia.

1950 Atlantic hurricane season

The 1950 Atlantic hurricane season was the first year in the Atlantic hurricane database (HURDAT) that storms were given names in the Atlantic basin. Names were taken from the Joint Army/Navy Phonetic Alphabet, with the first named storm being designated "Able", the second "Baker", and so on. It was an active season with sixteen tropical storms, with eleven of them developing into hurricanes. Six of these hurricanes were intense enough to be classified as major hurricanes—a denomination reserved for storms that attained sustained winds equivalent to a Category 3 or greater on the present-day Saffir–Simpson scale. One storm, the twelfth of the season, was unnamed and was originally excluded from the yearly summary, and three additional storms were discovered in re-analysis. The large quantity of strong storms during the year yielded, prior to modern reanalysis, what was the highest seasonal accumulated cyclone energy (ACE) of the 20th century in the Atlantic basin; 1950 held the seasonal ACE record until broken by the 2005 Atlantic hurricane season. However, later examination by researchers determined that several storms in the 1950 season were weaker than thought, leading to a lower ACE than assessed originally.The tropical cyclones of the season produced a total of 88 fatalities and $38.5 million in property damage (1950 USD). The first officially named Atlantic hurricane was Hurricane Able, which formed on August 12, brushed the North Carolina coastline, and later moved across Atlantic Canada. The strongest hurricane of the season, Hurricane Dog, reached the equivalent of a Category 4 hurricane on the Saffir–Simpson scale, and caused extensive damage to the Leeward Islands. Two major hurricanes affected Florida: Easy produced the highest 24-hour rainfall total recorded in the United States, while King struck downtown Miami as a Category 4 hurricane and caused $27.75 million (1950 USD) of damage. The two major landfalls made the 1945–1950 period the only five-year period to feature five major hurricane landfalls in the United States—a record that held until tied in 2000–2005. The last storm of the year, an unnamed tropical storm, dissipated on November 13.

1977 Pacific hurricane season

The 1977 Pacific hurricane season stands alongside 2010 as the least active Pacific hurricane season since reliable records began in 1971. Only eight tropical storms formed throughout the year; four further intensified into hurricanes, yet none strengthened into major hurricanes—a Category 3 or stronger on the Saffir–Simpson scale—an occurrence not seen again until 2003. Most tropical cyclones remained over the open eastern Pacific; however, the remnants of hurricanes Doreen and Heather led to heavy rainfall which damaged or destroyed structures and flooded roadways throughout the Southwest United States. Notably, Hurricane Anita which originally formed in the Gulf of Mexico made the rare trek across Mexico into the eastern Pacific, briefly existing as a tropical depression. Eight deaths were recorded while damage reached $39.6 million (1977 USD).

1978 Pacific hurricane season

The 1978 Pacific hurricane season officially began May 15, 1978, in the eastern Pacific, June 1, 1978, in the central Pacific, and officially ended on November 30, 1978. These dates conventionally delimit the period of time when tropical cyclones form in the eastern north Pacific Ocean.

Activity this year was slightly above-average, with eighteen named storms forming. Five of those were tropical storms, thirteen were hurricanes, and six were major hurricanes that reached Category 3 or higher on the Saffir–Simpson scale. In the Central Pacific, a tropical depression and a major hurricane formed. Also, this season is the fourth-most active season within the basin when calculating by ACE Index, as the season had an index of 207. Atlantic Hurricane Greta crossed into the basin and was renamed Olivia. The 1978 Pacific Hurricane Season was the first season on record to have an ACE total at least 200; it rests at 207 units.

Cyclone Kelvin

Severe Tropical Cyclone Kelvin was a strong tropical cyclone that impacted Western Australia in February 2018. The system was first identified as a weak tropical low on the morning of 11 February over the Northern Territory's Tiwi Islands by the Bureau of Meteorology. The low moved southwestwards over land and emerged over the Indian Ocean near Broome on 16 February. The storm intensified into a Category 1 tropical cyclone on the following day, becoming the sixth named cyclone of the 2017–18 season. Kelvin subsequently moved slowly eastwards and proceeded to rapidly intensify in the hours prior to landfall. The system crossed the coast along Eighty Mile Beach as a Category 3 severe tropical cyclone on the Australian scale, and a high-end Category 1 hurricane-equivalent cyclone on the Saffir-Simpson scale. Kelvin weakened at a very slow rate over the next few days, and was downgraded to a tropical low on 19 February.

Kelvin brought widespread heavy rainfall to the Kimberley region which had already been saturated by other tropical cyclone systems. As a result, significant flooding occurred in parts of the Kimberley, including in the towns of Broome and Bidyadanga. Property damage was sustained at Broome and Anna Plains Station, where the cyclone made landfall, as well as infrastructural damage to the Great Northern Highway as a result of the heavy rainfall and flooding.

Cyclone Sidr

Cyclone Sidr (JTWC designation: 06B, also known as Extremely Severe Cyclonic Storm Sidr) was a tropical cyclone that resulted in one of the worst natural disasters in Bangladesh. The fourth named storm of the 2007 North Indian Ocean cyclone season, Sidr formed in the central Bay of Bengal, and quickly strengthened to reach peak 1-minute sustained winds of 260 km/h (160 mph), making it a Category-5 equivalent tropical cyclone on the Saffir-Simpson Scale. The storm eventually made landfall in Bangladesh on November 15, 2007, causing large-scale evacuations. At least 3,447 deaths have been blamed on the storm, with some estimates reaching 15,000.Save the Children estimated the number of deaths associated with the cyclone to be between 3,100 and 10,000, while the Red Crescent Society reported on November 18 that the number of deaths could be up to 15,000. Other aid agencies have estimated a death toll of up to 15,000. International groups pledged US$95 million to repair the damage, which was estimated at $1.7 billion (2007 USD).

Herbert Saffir

Herbert Seymour Saffir (29 March 1917 – 21 November 2007) ( (listen)) was an American civil engineer who co-developed (with meteorologist Robert Simpson) the Saffir–Simpson Hurricane Scale for measuring the intensity of hurricanes. As recently as 2005 Saffir was the principal of Saffir Engineering in Coral Gables, Florida. He also published articles on designing buildings for high wind resistance.

Hurricane Dennis

Hurricane Dennis was an early-forming major hurricane in the Caribbean and Gulf of Mexico during the record-breaking 2005 Atlantic hurricane season. Dennis was the fourth named storm, second hurricane, and first major hurricane of the season. Forming in July, the hurricane became the strongest Atlantic hurricane ever to form before August at the time, a title it held for only six days before being surpassed by Hurricane Emily.

Dennis made landfall in Cuba twice as a Category 4 hurricane on the Saffir-Simpson scale and made landfall on the United States' Florida Panhandle as a Category 3 storm, coming less than a year after the devastating Hurricane Ivan. Dennis killed 88 people in total and was responsible for $2.5 billion (2005 USD) in damages to the United States, not counting additional damage in the Caribbean.

Hurricane Dog (1950)

Hurricane Dog was the most intense hurricane in the 1950 Atlantic hurricane season. Prior to reanalysis by the Hurricane Research Division in 2014, it was considered one of the strongest Atlantic hurricanes on record, equivalent to Category 5 status on the modern Saffir-Simpson scale, with winds of 185 miles per hour (298 km/h). The fourth named storm of the season, Dog developed on August 30 to the east of Antigua; after passing through the northern Lesser Antilles, it turned to the north and intensified into a Category 4 hurricane. Dog reached its peak intensity with winds of 145 mph (230 km/h) over the open Atlantic, and after weakening it passed within 200 miles (320 km) of Cape Cod, Massachusetts. The storm became extratropical on September 12.

Hurricane Dog caused extensive damage to the Leeward Islands, and was considered the most severe hurricane on record in Antigua. Many buildings were destroyed or severely damaged on the island, with thousands left homeless just weeks after Hurricane Baker caused serious damage there. In the United States, the hurricane caused moderate coastal damage, including damage to several boats, and resulted in 11 offshore drownings. Strong winds caused widespread power outages across southeastern New England. There were twelve people missing and assumed dead offshore Nova Scotia. Damage across its path totaled about $3 million (1950 USD, $26.8 million 2009 USD).

Hurricane Gert (2017)

Hurricane Gert was a strong tropical cyclone that brought heavy surf and rip currents to the East Coast of the United States in August 2017. Gert originated from a tropical wave that moved off the coast of Africa on August 3 yet failed to organize significantly until August 12, when the system coalesced into a tropical depression east of the Bahamas. A few hours later, the depression became the seventh tropical storm of the annual hurricane season and was named Gert. For the next day, though, further intensification was hindered by the proximity of dry air. Once Gert was able to overcome that on August 14, however, Gert resumed strengthening while moving northwards, paralleling the United States coastline. Gert reached its peak intensity on August 16 at Category 2 status on the Saffir–Simpson scale as it accelerated northeastwards. Thereafter, increasing vertical wind shear and decreasing sea surface temperatures caused Gert to rapidly weaken and transition into an extratropical cyclone on August 17, well east of Atlantic Canada. The remnants of Gert dissipated late on August 18, after they merged with another extratropical cyclone over the open Atlantic.

During its lifetime, Gert brought heavy swells, rough surf, and rip currents to the East Coast of the United States and Atlantic Canada. Two fatalities occurred when two swimmers drowned amid heavy surf. The extratropical system that merged with the remnants of Gert went on to bring strong winds and rain to Ireland and parts of the United Kingdom.

Hurricane Katia (2017)

Hurricane Katia was the most intense hurricane in the Bay of Campeche since Hurricane Karl in 2010. The eleventh named storm and sixth hurricane of the unusually active 2017 Atlantic hurricane season, Katia originated on September 5, out of a broad low-pressure area that formed in the Bay of Campeche. Located in an area of weak steering currents, Katia meandered around in the region, eventually intensifying into a hurricane on September 6. The nascent storm eventually peaked as a 105 mph (165 km/h) Category 2 hurricane on the Saffir–Simpson scale while it began to move southwestward. However, land interaction began to weaken the hurricane as it approached the Gulf Coast of Mexico. Early on September 9, Katia made landfall near Tecolutla at minimal hurricane intensity. The storm quickly dissipated several hours later, although its mid-level circulation remained intact and later spawned what would become Hurricane Otis in the Eastern Pacific.

At least 53 municipalities in Mexico were affected by Katia. Heavy rainfall left flooding and numerous mudslides, with 65 mudslides in the city of Xalapa alone. Although damage estimates were unknown, preliminary reports indicated that 370 homes were flooded. Three deaths were confirmed to have been related to the hurricane, with two from mudslides and one from being swept away in floodwaters. Approximately 77,000 people were left without power at the height of the storm. Coincidentally, the storm struck Mexico just days after a major earthquake struck the country, worsening the aftermath and recovery. Hurricane Katia marked the first instance of three simultaneously active hurricanes since 2010. Katia's peak marked the second known time in Atlantic history and the first time since 1893 that three simultaneously active storms were at least of Category 2 strength.

Hurricane Olivia (1975)

Hurricane Olivia was considered the worst hurricane to hit Mazatlán, Sinaloa since 1943, in addition to being the strongest landfalling and costliest hurricane of the 1975 Pacific hurricane season. Olivia formed on October 22 to the south of Mexico, quickly intensifying into a tropical storm. The storm moved northwestward initially, followed by a northeast turn. On October 23, Olivia attained hurricane status, and the next day reached Category 3 intensity on the Saffir-Simpson scale just before moving ashore Mazatlán in northwest Mexico. Olivia destroyed 7,000 houses in the region, leaving 30,000 people homeless, and damage totaled $20 million (1975 USD, $93.1 million 2019 USD). The hurricane killed 30 people, 20 of them from drowning in shrimp boats.

Hurricane Paul (2006)

Hurricane Paul was a hurricane that ultimately struck Mexico as a tropical depression in October 2006. It developed from an area of disturbed weather on October 21, and slowly intensified as it moved into an area of warm waters and progressively decreasing wind shear. Paul attained hurricane status on October 23, and later that day it reached its peak intensity of 105 mph (165 km/h), a strong Category 2 hurricane on the Saffir-Simpson scale. A strong trough turned the hurricane to the north and northeast into an area of strong vertical shear, and Paul weakened to a tropical storm on October 24. It accelerated northeastward, and after passing a short distance south of Baja California Sur the low level circulation became decoupled from the rest of the convection. Paul weakened to a tropical depression on October 25 a short distance off the coast of Mexico, and after briefly turning away from the coast it made landfall on northwestern Sinaloa on October 26.

Paul was the third hurricane to threaten western Mexico in the season, the others being Hurricanes John and Lane. Rough surf killed two people along Baja California Sur, while flooding was reported in Sinaloa. Damage totaled more than $35 million (2006 MXN, $3.2 million 2006 USD).

Maximum sustained wind

The maximum sustained wind associated with a tropical cyclone is a common

indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a distance defined as the radius of maximum wind, or RMW. Unlike gusts, the value of these winds are determined via their sampling and averaging the sampled results over a period of time. Wind measuring has been standardized globally to reflect the winds at 10 metres (33 ft) above the Earth's surface, and the maximum sustained wind represents the highest average wind over either a one-minute (US) or ten-minute time span (see the definition, below), anywhere within the tropical cyclone. Surface winds are highly variable due to friction between the atmosphere and the Earth's surface, as well as near hills and mountains over land.

Over the ocean, satellite imagery determines the value of the maximum sustained winds within a tropical cyclone. Land, ship, aircraft reconnaissance observations, and radar imagery can also estimate this quantity, when available. This value helps determine damage expected from a tropical cyclone, through use of such scales as the Saffir–Simpson scale.

Typhoon Francisco (2013)

Typhoon Francisco, known in the Philippines as Typhoon Urduja, was a powerful typhoon that strengthened to the equivalent of a Category 5 on the Saffir-Simpson scale, according to the Joint Typhoon Warning Center. The 25th named storm and the 10th typhoon of the 2013 Pacific typhoon season, Francisco formed on October 16 east of Guam from a pre-existing area of convection. With favorable conditions, it quickly intensified into a tropical storm before passing south of Guam. After stalling to the southwest of the island, Francisco turned to the northwest into an environment of warm waters and low wind shear, becoming a typhoon. The JTWC upgraded it to super typhoon status on October 18, while the Japan Meteorological Agency (JMA) estimated peak 10‑minute sustained winds of 195 km/h (120 mph). Gradual weakening ensued, and after the typhoon turned to the northeast, Francisco deteriorated into a tropical storm on October 24. Passing southeast of Okinawa and mainland Japan, the storm accelerated and became extratropical on October 26, dissipating later that day.

On Guam and in the Northern Marianas Islands, Francisco produced tropical storm force wind gusts, strong enough to knock over some trees and cause $150,000 (2013 USD) in damage. The typhoon also dropped heavy rainfall on Guam, peaking at 201 mm (7.90 in) at Inarajan. Later, Francisco brought gusty winds and some rainfall to Okinawa. In Kagoshima Prefecture, 3,800 homes lost power, while an island-wide evacuation advisory was issued for Izu Ōshima after Typhoon Wipha spawned a deadly mudslide a week prior. Rains in Japan peaked at 600 mm (24 in) in Niyodogawa, Kōchi on Shikoku.

Typhoon Wayne (1986)

Typhoon Wayne, known in the Philippines as Typhoon Miding, is one of the longest-lived tropical cyclones on record in the north-western Pacific Ocean. The system meandered for 21 days in August–September 1986 between the South China Sea and far western tropical North Pacific Ocean, staying within the monsoon trough and causing heavy rains across the Philippines, Taiwan, southeast China, Hainan Island, and Vietnam. Its maximum sustained winds peaked at category two strength on the Saffir–Simpson scale. Various signals were raised for Hong Kong three times due to Wayne's unusual track. A total of 490 perished, and the storm caused US $399 million (1986 US dollars) in damage.

Witch of November

The Witch of November, or November Witch, refers to the strong winds that frequently blow across the Great Lakes in autumn. The "witches" are caused by intense low atmospheric pressure over the Great Lakes pulling cold Canadian/Arctic air from the north or northwest and warm Gulf air from the south. When these cold and warm air masses collide, they can result in hurricane force winds that stir up large waves on the lakes.

Gordon Lightfoot's song "The Wreck of the Edmund Fitzgerald" makes reference to the Witch of November: the storm that wrecked the Edmund Fitzgerald was 978 mbar, equivalent to a borderline Category 1/2 hurricane. Similar witches have caused numerous shipwrecks over the years. Another storm that hit in November 1998 was 967 mbar, equivalent to a solid Category 2 hurricane. A still stronger storm, of October 2010, brought Minnesota and Wisconsin record low barometric pressures of, respectively, 954.96 and 961.06 mbar (both equivalent to a category 3 hurricane on the Saffir-Simpson scale) and lashed Duluth with 81 mph wind gusts and 19-foot seas during the night of October 26–27, 2010.

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