Hurricanes are large tropical storms that form over warm ocean waters and contain heavy winds and rainfall. They typically form where ocean waters are at least 80 degrees Fahrenheit and 150 feet deep. One to six hurricanes may strike the United States in a given year, causing billions of dollars in damage from flooding and winds. The most destructive hurricane was Hurricane Katrina, which caused catastrophic flooding and destruction in New Orleans. The Atlantic Ocean and Gulf of Mexico are most prone to hurricanes.