How Are Typhoon Categories Defined? A Visual Guide from Tropical Depression to Super Typhoon
China classifies tropical cyclones into six categories: tropical depression, tropical storm, severe tropical storm, typhoon, severe typhoon, and super typhoon, based on the maximum sustained wind speed near the center.
China's Tropical Cyclone Classification System
According to the national standard "Classification of Tropical Cyclones" (GB/T 19201-2006), tropical cyclones are divided into six levels based on the maximum average wind speed near the surface center:
| Category | Maximum Wind Speed | Beaufort Scale |
|---|---|---|
| Tropical Depression (TD) | 10.8-17.1 m/s | Force 6-7 |
| Tropical Storm (TS) | 17.2-24.4 m/s | Force 8-9 |
| Severe Tropical Storm (STS) | 24.5-32.6 m/s | Force 10-11 |
| Typhoon (TY) | 32.7-41.4 m/s | Force 12-13 |
| Severe Typhoon (STY) | 41.5-50.9 m/s | Force 14-15 |
| Super Typhoon (SuperTY) | ≥51.0 m/s | Force 16 and above |
What Do These Wind Speeds Mean?
- 17.2 m/s (Force 8): Difficult to walk against the wind; tree branches break
- 32.7 m/s (Force 12): Rare on land; highly destructive
- 51 m/s (Force 16): Approximately 184 km/h, close to high-speed rail speeds
- The strongest typhoons in history, such as Typhoon Haiyan in 2013, had estimated peak wind speeds exceeding 70 m/s
"Typhoon Number" vs. "Typhoon Category"
- Number (e.g., 202509): The 9th tropical cyclone of the year to reach tropical storm strength; acts as its "ID number"
- Category (e.g., Super Typhoon): Indicates intensity level, which changes continuously as the typhoon develops
A typhoon's intensity changes throughout its lifecycle: it typically forms as a tropical depression, intensifies over the ocean to reach its peak, and rapidly weakens after landfall. The track maps on TyphoonSays use different colors to mark the intensity category at each point along the path, providing an intuitive view of the complete intensity evolution.
International Standards
The United States uses the Saffir-Simpson Hurricane Wind Scale (Categories 1-5), while the Japan Meteorological Agency (JMA) has its own classification system. The same typhoon may be assigned different intensities by different countries due to variations in wind speed averaging periods (China uses 2-minute averages, Japan uses 10-minute averages, and the US uses 1-minute averages). Consequently, US 1-minute average wind speeds often appear higher.