How Rare are Category 5 Hurricanes?

View of Category 5 Hurricane Ivan from Space Station in 2004  (Source: NASA)

Hurricane season runs a full six months from June 1 through November 30 in the Atlantic Ocean, with September being the busiest month.  That’s because atmospheric conditions are the most favorable in September with ample warm ocean water and little or no wind shear (winds that change directions with altitude) in the tropics.  A tropical storm becomes a hurricane when the sustained winds around the center of the storm reach 74 mph.

The intensity of a hurricane is measured on the “Saffir-Simpson Scale.”  A Category 1 hurricane is considered “minimal,” while a Category 5 is as strong as a hurricane gets – capable of “catastrophic” damage.  Category 5 hurricanes only occur under the rarest of circumstances when atmospheric and environmental conditions are their most favorable.

The past decade from 2001 to 2010 saw the highest number of Category 5 hurricanes on record.  According to the National Hurricane Center, a total of eight Category 5 hurricanes developed in the Atlantic Ocean Basin from 2001 to 2010.  Prior to that, the previous highest total of Category 5 hurricanes measured by decade was six, which occurred twice (in the 1930s and the 1960s).  Since 1920, the Atlantic Ocean has averaged approximately four Category 5 hurricanes per decade.

Although the last decade saw the highest number of Category 5 hurricanes on record, none have developed in the Atlantic Ocean since 2007.  The current streak of eight years since the last Atlantic Category 5 hurricane has tied the second longest streak for length of time in between these rare storms.  In 1988, Hurricane Gilbert became the first Category 5 in the Atlantic since Hurricane Allen in 1980.  The longest streak in between Category 5 hurricanes in the Atlantic Ocean is 15 years – in between the 1938 hurricane that struck New England and Hurricane Carol in 1953.  

There are two important distinctions to consider, though, when I mention this 15 year streak.  Weather satellites weren’t operational until the 1960s.  Prior to the advent of weather satellites, the only way to tell if there was a hurricane was if it made landfall or if there happened to be a ship in its path.  The U.S. Air Force Reserve began flying hurricane “reconnaissance” flights in 1944.  Aside from a landfall, a hurricane reconnaissance flight is the most accurate way to measure the intensity of a hurricane.  There may have been more Category 5 hurricanes that developed in between the 1938 storm (prior to when tropical storms and hurricanes began receiving names) and 1953, but there was no way to tell they existed if they developed over the open ocean.  So given this uncertainty, this 15 year streak should be taken with a grain of salt.

The current eight year streak without a Category 5 hurricane in the Atlantic Ocean remains active.  The United States has been relatively fortunate, too, without a landfall from a major hurricane (Category 3 or higher) since 2005.  Although the United States has had some very destructive hurricanes since then (such as Ike in 2008 and Irene in 2011), they weren’t major storms.