A total of 33 recorded tropical cyclones have reached Category 5 strength on the Saffirâ€"Simpson hurricane wind scale in the Atlantic Ocean north of the equator, the Caribbean Sea, and the Gulf of Mexico. Hurricanes of such intensity occur once every three years in this region on average.
Only six timesâ€"in the 1932, 1933, 1961, 2005, 2007, and 2017 hurricane seasonsâ€"has more than one Category 5 recorded hurricane formed. Only in 2005 have more than two Category 5 hurricanes formed, and only in 2007 and 2017 did more than one make landfall at Category 5 strength.
Background
A Category 5 Atlantic hurricane is one that is considered by the United States National Hurricane Center (NHC), to have had sustained wind speeds greater than 136 knots (157 mph; 252 km/h; 70 m/s) on the Saffirâ€"Simpson scale. The NHC considers sustained wind speeds to be those that occur over a one-minute period at 10 metres (32.8 ft) above ground. These wind speeds are estimated by using a blend of data from a variety of sources, which include observations from nearby ships, reconnaissance aircraft, or automatic weather stations and pictures from various satellites.
Between 1924 and 2017, 33 hurricanes were recorded at Category 5 strength. No Category 5 hurricanes were observed officially before 1924. It can be presumed that earlier storms reached Category 5 strength over open waters, but the strongest winds were not measured. The anemometer, a device used for measuring wind speed, was invented in 1846. However, during major hurricane strikes the instruments as a whole were often blown away, leaving the hurricane's peak intensity unrecorded. For example, as the Great Beaufort Hurricane of 1879 struck North Carolina, the anemometer cups were blown away when indicating 138 mph (222 km/h).
A reanalysis of weather data is ongoing by researchers who may upgrade or downgrade other Atlantic hurricanes currently listed at Categories 4 and 5. For example, the 1825 Santa Ana hurricane is suspected to have reached Category 5 strength. Furthermore, paleotempestological research aims to identify past major hurricanes by comparing sedimentary evidence of recent and past hurricane strikes. For example, a "giant hurricane" significantly more powerful than Hurricane Hattie (Category 5) has been identified in Belizean sediment, having struck the region sometime before 1500.
Officially, the decade with the most Category 5 hurricanes is 2000â€"2009, with eight Category 5 hurricanes having occurred: Isabel (2003), Ivan (2004), Emily (2005), Katrina (2005), Rita (2005), Wilma (2005), Dean (2007), and Felix (2007). The previous decades with the most Category 5 hurricanes were the 1930s and 1960s, with six occurring between 1930 and 1939 (before naming began).
Nine Atlantic hurricanesâ€"Camille, Allen, Andrew, Isabel, Ivan, Dean, Felix, Irma and Mariaâ€"reached Category 5 intensity on more than one occasion; that is, by reaching Category 5 intensity, weakening to a Category 4 or lower, and then becoming a Category 5 again. Such hurricanes have their dates shown together. Camille, Andrew, Dean, Felix, Irma, and Maria each attained Category 5 status twice during their lifespans. Allen, Isabel, and Ivan reached Category 5 intensity on three separate occasions. However, no Atlantic hurricane has reached Category 5 intensity more than three times during its lifespan. The November 1932 Cuba hurricane holds the record for most time spent as a Category 5 (although it took place before satellite or aircraft reconnaissance, so this record may be somewhat suspect). Irma holds the record for longest continuous span as a Category 5 in the satellite era.
Thirty-three Category 5s have been recorded in the Atlantic basin since 1851, when records began. Only one Category 5 has been recorded in July, eight in August, nineteen in September, five in October, and one in November. There have been no officially recorded June or off-season Category 5 hurricanes.
The July and August Category 5s reached their high intensities in both the Gulf of Mexico and the Caribbean Sea. These are the areas most favorable for tropical cyclone development in those months.
September sees the most Category 5 hurricanes. This coincides with the climatological peak of the Atlantic hurricane season, which occurs in early September. September Category 5s reached their strengths in any of the Gulf of Mexico, Caribbean Sea, and open Atlantic. These places are where September tropical cyclones are likely to form. Many of these hurricanes are either Cape Verde-type storms, which develop their strength by having a great deal of open water; or so-called Bahama busters, which intensify over the warm Loop Current in the Gulf of Mexico.
All six Category 5s in October and November reached their intensities in the western Caribbean, a region that Atlantic hurricanes strongly gravitate toward late in the season. This is due to the climatology of the area, which sometimes has a high-altitude anticyclone that promotes rapid intensification late in the season, as well as warm waters.
Systems
Listed by month
Landfalls
All Atlantic Category 5 hurricanes have made landfall at some location at hurricane strength. Most Category 5 hurricanes in the Atlantic make landfall because of their proximity to land in the Caribbean and Gulf of Mexico, where the usual synoptic weather patterns carry them towards land, as opposed to the westward, oceanic mean track of Eastern Pacific hurricanes. Sixteen of the storms made landfall while at Category 5 intensity; 2007 and 2017 are the only years in which two storms made landfall at this intensity.
Many of these systems made landfall shortly after weakening from a Category 5. This weakening can be caused by dry air near land, shallower waters due to shelving, interaction with land, or cooler waters near shore. In southern Florida, the return period for a Category 5 hurricane is roughly once every 50 years.
The following table lists these hurricanes by landfall intensity.
See also
- List of Atlantic hurricanes
- List of Atlantic hurricane seasons
- List of Category 4 Atlantic hurricanes
- List of Category 5 Pacific hurricanes
- List of Category 4 Pacific hurricanes
References
External links
- NHC web site
