The Saffir–Simpson Hurricane Wind Scale (SSHWS), classifies hurricanes – Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms – into five categories distinguished by the intensities of their sustained winds.
- Tropical depression: The first stage of a tropical weather event is called a tropical depression. Meteorologists sometimes refer to these formations as a tropical wave, disturbance, feature, system or disturbance. Tropical depressions are cyclones with winds that gust at 38 miles per hour (33 knots) or less. While cyclones aren’t as strong as tropical storms or hurricanes, they can bring significant amounts of rain, thunderstorms and devastating floods.
- Tropical storm: Meteorologists upgrade a tropical depression to a tropical storm when the cyclone’s circulation is more organized and has sustained wind speeds of 39 to 73 miles per hour (34 to 63 knots). Tropical storms produce large amounts of rain, and can cause enough wind and wave activity to damage boats and erode beaches. When a weather event qualifies as a tropical storm, meteorologists categorize it according to the Saffir-Simpson Scale.