The Answer:

During World War II, meteorologists in the US Army Air Corps and the US Navy began unofficially naming tropical storms after their wives and girlfriends. In 1953, the US Weather Bureau officially started giving tropical storms women's names in order to simplify public reports and distinguish storms from each other. Storms were not given male names until 1978. Today, storm names are recycled every six years and alternate between male and female. The names of particularly vicious storms—like hurricanes Andrew, Hugo, and Katrina—are retired, and new names are added to the list in their place.

—The Fact Monster