List of Category 5 Pacific hurricanes
until 2018. Note that parts of some tracks cross the Date Line and are omitted.
Category 5 hurricanes are tropical cyclones that reach Category 5 intensity on the Saffir–Simpson Hurricane Scale. They are by definition the strongest hurricanes that can form on planet Earth. They are rare in the northeastern Pacific Ocean and generally form only once every several years. In general, Category 5s form in clusters in single years. Landfalls by such storms are rare due to the generally westerly path of tropical cyclones in the northern hemisphere.
Statistics
A Category 5 hurricane is defined as having sustained windspeeds of at least 137 knots over a one-minute period above the ground. As a tropical cyclone is moving, its wind field is asymmetric. In the northern hemisphere, the strongest winds are on the right side of the storm. The highest winds given in advisories are those from the right side.Since the 1959 season, only 18 hurricanes are known to have reached Category 5 intensity. There are no known Category 5 storms occurring before 1959. It is possible that some earlier storms reached Category 5 over open waters, but they were never recognized because they never affected land and remained at sea.
Category 5 Pacific hurricanes
This lists all of the Category 5 hurricanes in the order in which they formed. Only 1994's Hurricane Emilia and 2006's Hurricane Ioke have reached Category 5 intensity more than once; that is, by weakening into a Category 4 or weaker storm and later re-strengthening to a Category 5 storm.Before the advent of reliable geostationary satellite coverage in 1966, the number of eastern Pacific tropical cyclones was significantly underestimated. It is therefore very possible that there are additional Category 5 hurricanes other than those listed, but they were not reported and therefore not recognized. However, the lack of Pacific Category 5 hurricanes during the late 1970s, 1980s, and early 1990s, is certain.
The minimum central pressure of these storms is, for the most part, estimated from satellite imagery using the Dvorak technique. In the case of Kenna, Ava, Patricia, and Lane, the central pressure was measured by hurricane hunter aircraft flying into the storm. Because of the estimation of central pressures, it is possible that other storms more intense than these have formed.
The reason for estimating the pressure is the fact that most of these storms did not threaten land. As Kenna, Patricia and Lane were threatening land, their pressures were measured by Hurricane Hunters using dropsondes. While Hurricane Ava never threatened land, it too was flown into by Hurricane Hunters to test equipment and conduct research.
Older storms have incomplete pressure readings, since there were no satellite-based estimates; the only observations were taken by ships, land-based observations, or reconnaissance aircraft when available. Ava's minimum known pressure was measured when it was a Category 4 hurricane, for example. John and Gilma have incomplete pressures because the Central Pacific Hurricane Center, in general, did not publish pressure on systems in the central Pacific at the time. This list is not identical to the list of most intense Pacific hurricanes. The most intense known Category 4 storm in the eastern Pacific was 2014's Odile. The lowest pressure of this storm was 918 millibars, lower than that of some Category 5's, such as Guillermo.
Hurricanes have reached Category 5 intensity during every month from June to October. The earliest Category 5 to form in a season is 1973's Hurricane Ava, which formed on June 7. The latest Category 5 to form in a season is Hurricane Kenna, which reached peak intensity on October 24. Hurricanes Ava, Gilma, Ioke, Linda, and Patricia are the most intense storms to form in their respective months. There have been no May, November, or off-season Category 5 hurricanes.
Two Pacific hurricanes are known to have reached Category 5 intensity multiple times: Emilia and Ioke. Both did it twice, and Ioke reached Category 5 status a third time as a typhoon while in the western Pacific. Hurricane Ioke was tied for the longest-lasting Category 5 hurricane recorded, spending 42 hours at that strength, while hurricanes John and Linda had the longest time spent consecutively at that intensity.
radar in the tail of a C130 during a flight into Hurricane Ava.
Climatology
In the eastern Pacific, Category 5 hurricanes usually occur only in El Niño years. During El Niño years, conditions are more favorable for tropical cyclones because of warmer sea surface temperatures and reduced wind shear. This is why Category 5 hurricanes cluster in single seasons, with half of the known Category 5 hurricanes having occurred in the 1994, 2002, and 2018 seasons-the three seasons with the most Category 5 hurricanes, at three each. The effects of El Niño are most significant in the central Pacific.The general lack of Category 5s in non warm-ENSO years is because of there being limited space for development. The prevailing ocean currents of the area carry warm water to the west. As there is no large piece of land to block the water and cause it to "pile up" like in the Atlantic, the area suitable for all tropical cyclones is small. Farther out to sea, while waters are still warm, wind shear limits the development of tropical cyclones in the waters south of Hawaii. This makes an otherwise ideal region unfavorable for tropical cyclones.
This does not mean that a Category 5 hurricane cannot form outside of an El Niño event. The entire year of 1959 was neither an El Niño or a La Niña, but it had one Category 5 hurricane. Most of 1973 was during a La Niña, which reduces tropical cyclone activity in the eastern Pacific, yet Hurricane Ava, a Category 5 hurricane, formed in June of that year.
The 2009, 2010, 2014, and 2015 seasons are the only pairs of seasons in which a Category 5 hurricane formed in consecutive years.
Landfalls
Of all of the Category 5 Pacific hurricanes, the only ones to make landfall at any intensity were Hurricane Kenna, Hurricane Rick, Hurricane Patricia, and Hurricane Willa. None made landfall as Category 5 hurricanes; Patricia and Kenna had weakened to Category 4 status at the time of their landfalls, Willa had weakened to Category 3, and Rick was a tropical storm at its landfall. Patricia was the strongest at landfall among Pacific hurricanes; 1976's Hurricane Madeline and 1992's Hurricane Iniki are tied as the second-strongest storms at landfall, both of which did not reach Category 5 strength, but made landfall as stronger Category 4 storms than Kenna. Originally, a hurricane in 1959 was thought to have struck Manzanillo at Category 5 intensity, but a reanalysis in 2016 indicated the storm had peaked as a Category 4 hurricane, and made landfall with the same sustained wind speed as Kenna. Patricia was also originally thought to have made landfall as a Category 5 hurricane near Manzanillo before post-season analysis in 2016.In addition to these four systems, hurricanes John, Linda, Ioke, Lane, and Walaka all threatened land at some point during their existence. John, Ioke and Walaka had minimal impacts on Johnston Atoll, John caused heavy surf in Hawaii, and Walaka passed close to East Island in the French Frigate Shoals. Linda was briefly forecast to approach southern California, and it passed close to Socorro Island near peak intensity. Out of the five aforementioned hurricanes, Lane had the most significant impact on land, threatening Hawaii as a major hurricane, and dropping more than of rain across many areas.
The reason for the lack of landfalls is that tropical cyclones in the northern hemisphere usually travel to the west. In the Atlantic, this sends hurricanes towards North America. In the eastern Pacific, this sends tropical cyclones out into the open ocean to dissipate over waters too cool to support them or in environments with high wind shear. Hawaii, the only heavily populated island chain in the eastern Pacific, is protected from most hurricanes by a subtropical ridge and because its land area is small relative to the total ocean area where hurricanes form and travel.