Classification of tropical cyclones

Tropical cyclones above a particular wind speed are classified for public safety. 

Depending on the maximum sustained wind speed, tropical cyclones are designated as follows:

• Tropical depression is when the maximum sustained wind speed is less than 63 km/h.
• Tropical storm is when the maximum sustained wind speed is more than 63 km/h. It is then also given a name.
• Hurricane, typhoon, tropical cyclone, very severe cyclonic storm - depending on the basin - when the maximum sustained wind speed exceeds 116 km/h or 63 knots.

Further information:  

Guidelines for converting between various wind averaging periods in tropical cyclone conditions.