Hurricanes tend to arrive at the end of summer or in early fall. These powerful, erratic, destructive storms can be full of tricks, however, and are not very predictable from year to year. Over the long term, though, September is the most common month for hurricanes in the United States and is also the month when hurricanes have done the most damage.
The National Hurricane Center, part of the National Weather Service, defines the hurricane season on the Atlantic coast of the United States (including the Gulf Coast) as the first day of June through the last day of November. Hurricanes are less common in the Pacific Ocean, but the Pacific hurricane season, according to the NHC, is actually a few weeks longer, from May 15 through the end of November.
The NHC list of "Hurricanes in History" includes most major hurricanes since 1900. September was the most common month for hurricanes listed by NHC, with 15 major storms. August was second most common month, with 12 hurricanes. According to a more extensive count of storms conducted by Stormfax for the period 1851 through 2006, there were 96 hurricanes: 44 in September and 27 in August, with the remaining hurricanes in October, July and June. Conditions in September and August are particularly favorable for hurricane formation. Ocean temperatures have warmed and can provide the energy input needed for hurricane formation. At the same time, air-circulation conditions in the atmosphere are favorable for producing the large-scale spin needed for a hurricane to occur.
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Florida Is a Favorite Target
The Stormfax analysis also details the vulnerability of Florida as a target for hurricanes. The state experienced 45 hurricanes during the years 1851 to 2006, more than twice as many as Texas or Louisiana, which were each tied for second place with 20 hurricanes each.
NHC analyzed the economic damage caused by hurricanes during the period 1900 to 2005 and documented overall damage at $1.09 trillion. Not surprisingly, September -- the most costly month owing to the large number of storms -- accounted for $581 billion in damage. August storms added another $340 billion. Overall, September and August hurricanes accounted for 84 percent of the total damage.