Hurricane Classification

Tropical cyclones in the Atlantic basin are classified by their wind speeds according to the Saffir-Simpson scale. Hurricanes are categorized by their strongest winds from Category 1 to Category 5, with 5 being the strongest category. Tropical cyclones can form with wind speeds below hurricane strength: they are either classified as a tropical depression or a tropical storm, depending on how strong the wind speeds are. A storm system will be officially classified as a tropical cyclone by the National Hurricane Center in the Atlantic basin when it exhibits a complete circulation around the center of the storm and shows certain tropical characteristics.

Different classification systems are used by weather services outside the United States for tropical cyclones which occur in basins other than the Atlantic or Eastern Pacific. For example, tropical cyclones which occur in the Western Pacific are commonly referred to as typhoons, and they are classified by the Japan Meteorological Agency. Typhoons are also classified by their wind speeds, but they do not follow the same category system that the United States uses for hurricanes.