Hawaii Hurricanes: How Unusual Are They?

Hawaii may be paradise, but like the Caribbean Sea, hurricanes and tropical storms are part of its history.

On average, four to five tropical cyclones occur in the central Pacific Ocean basin (between 140-180 degrees west longitude) each year, according to Dr. Rick Knabb, director of the National Hurricane Center and former Hurricane Expert at The Weather Channel. About two-thirds of those systems come from the eastern Pacific basin.

Larger Hurricane Threat: Look South

Hawaii has been, and will be in the future, hit by hurricanes. The key, at least climatologically speaking, is the direction of the storm's approach.

As you can see in the track map above, virtually all hurricanes near the Hawaiian Islands since 1950 have approached from the southeast, south, or southwest. We have some of them labeled in the map above.

Sea-surface temperatures are typically warmer over this farther south trajectory. Any south or southwest wind aloft would steer a hurricane toward the island chain. Also, a hurricane simply rounding the southwest side of a less expansive eastern Pacific Ocean subtropical high would put Hawaii in the crosshairs.

In El Nino years, the trade winds that sometimes trap tropical cyclones well south of the islands relax, making these lingering storms south of the islands more susceptible to be drawn northward. Of course, an El Nino does not guarantee a hurricane will impact Hawaii. 

The costliest hurricane in Hawaii's history, Hurricane Iniki, originated in the eastern Pacific as Tropical Depression Eighteen-E on Sept. 5, 1992. The depression then crossed over into the central Pacific Ocean basin to the west of 140W longitude where it became a tropical storm and eventually a powerful hurricane. Again, note that track was initially well south of Hawaii, before it curled north.

The island of Kauai was especially hard hit by damaging winds. Along the southern coast, many structures were wiped out by storm surge flooding and large, battering waves.

Hurricane Flossie in 2007 is an example of a tropical cyclone that originated in the eastern Pacific and was aimed at the Big Island of Hawaii before it weakened dramatically due to wind shear. Hurricane watches and tropical storm warnings were issued since Flossie was forecast to maintain hurricane intensity as it arrived in the vicinity of the Big Island. Thankfully, Flossie weakened quicker than anticipated, resulting in minimal impacts outside of high surf and winds to 39 mph.

August is the peak month for tropical cyclones in the central Pacific basin, chalking up twice as many (74) as September (37) from 1971-2013, according to the Central Pacific Hurricane Center. Unlike the Atlantic Basin, July is the second most active month (45) in the central Pacific basin.

Dr. Knabb, a former deputy director at NOAA's Central Pacific Hurricane Center in Honolulu, points out that there is no meteorological reason why the core of a major hurricane can't directly hit Honolulu, resulting in destructive storm surge flooding, wind damage, and rainfall flooding affecting a metro population (minus tourists) of just under 400,000.

Don't Fear the East Most of the Time

Virtually every system approaching Hawaii from the east since 1950 tracking at least as far north as the latitude of the Big Island of Hawaii eventually weakened to a tropical storm or depression by the time it reached the islands. This included a large majority of those migrating from the eastern Pacific basin.

Dating to 1950, there is no record of a hurricane landfalling on the Big Island of Hawaii. Tropical Storm Iselle became only the second tropical storm, and the strongest, to landfall on the Big Island dating to 1950. The only other storm to do so was in 1958. Of course, in the vast Pacific Ocean, even the Big Island represents a pretty small target for the center of a tropical cyclone.

There are several reasons why this happens so often.

• Drier, more stable air from the subtropical high to the northeast of Hawaii eventually inhibits thunderstorms from persisting and remaining clustered near the cyclone's center.
• Wind shear (the change in wind speed and/or direction with height) is typically stronger near the Hawaiian islands, acting to displace thunderstorms from the cyclone's center.
• Cooler sea-surface temperatures in the Pacific waters to the east of the Big Island of Hawaii keep the air somewhat cooler above it, increasing the stability of the atmosphere, making it less susceptible to forming and maintaining thunderstorms.

Of course, this doesn't mean every single storm will do that in the future. This is the reality of a meteorological rule of thumb.

Below, we've plotted the named storms (tropical storms and hurricanes) tracking close to Hawaii from 1950-2013, according to the National Hurricane Center's "best track" database.

Note the tropical storm and depression tracks approaching the islands from the east, with at least as much latitude as the Big Island. This includes a few Category 4 eastern Pacific hurricanes that fizzled, such as Felicia (2009), Orlene (1992) and Raymond (1983).MORE ON WEATHER.COM: Hurricane Iniki (1992)