List of Category 5 Pacific Hurricanes - Climatology

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's cluster in single seasons. The effects of El Niño are most significant in the central Pacific (140°W to the dateline).

The general lack of Category 5's 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 cannot form outside of an El Niño event. The entire year of 1959 was neither an El Niño or a La Niña, but had two Category 5's (Patsy and the Mexico Hurricane) and was the deadliest Pacific hurricane season ever recorded in history. 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 season and the 2010 season are the only two seasons in which a Category 5 hurricane formed in consecutive years (Rick and Celia, respectively).