What Do the Grade 7 and Grade 10 Wind Circles of a Typhoon Mean?
TyphoonSays·防御问答 · Typhoon knowledge · 更新 at 2026-07-19
What Exactly Is a Wind Circle?
When checking typhoon warnings or track maps, you will often encounter the terms "Grade 7 Wind Circle" and "Grade 10 Wind Circle." Simply put, these represent the areas affected by different wind intensities on the periphery of a typhoon. According to the national standard "Tropical Cyclone Grades" issued by the China Meteorological Administration (CMA), a typhoon is a massive air vortex with uneven wind distribution: winds are strongest near the center and weaken as you move outward.
Meteorological departments typically define these circles based on the maximum average wind speed near the surface center. The Grade 7 Wind Circle refers to the boundary of the area where wind speeds reach or exceed 13.9 meters/second (Force 7 or higher); the Grade 10 Wind Circle refers to the boundary where wind speeds reach or exceed 24.5 meters/second (Force 10 or higher). You can imagine a typhoon as a spinning top: the Grade 10 Wind Circle is the "core damage zone" close to the center with extreme destructive power, while the Grade 7 Wind Circle is the wider "peripheral impact zone" where winds are strong enough to make it difficult to stand steadily.
What Risks Do Different Wind Circles Pose?
Understanding the size of these wind circles helps us intuitively assess the level of danger:
- Grade 7 Wind Circle (Strong Wind Warning Zone): When your location enters the Grade 7 Wind Circle, you will feel significant strong winds. At this stage, tree branches may break, billboards may shake, it becomes difficult for pedestrians to walk against the wind, and maritime navigation is significantly affected. This marks the beginning of substantial typhoon impacts and is the time to start preparing for wind protection.
- Grade 10 Wind Circle (Severe Damage Zone): Once inside the Grade 10 Wind Circle, the wind becomes extremely destructive. Large trees may be uprooted, temporary structures may collapse, windows face the risk of shattering, and outdoor activities become extremely dangerous or even impossible. For most residents, being within the Grade 10 Wind Circle means staying indoors in sturdy buildings and strictly avoiding going outside.
It is important to note that typhoon wind circles are not perfect circles. Influenced by terrain, movement speed, and other factors, they often appear elliptical or irregular, with the wind circle on the windward side typically larger than that on the leeward side.
How Should We Respond?
When forecasts indicate an approaching typhoon, pay attention to the coverage of the Grade 7 and Grade 10 Wind Circles. If your residence is expected to enter the Grade 7 Wind Circle, check doors and windows promptly, bring in potted plants or other items from balconies that could fall, and stock up on essential supplies. If the forecast indicates entry into the Grade 10 Wind Circle, prepare for the highest level of defense and ensure all personnel remain in safe indoor locations.
Regarding school and work suspensions, these are usually linked to the typhoon warning signals issued by local meteorological departments (such as Yellow, Orange, or Red warnings). Standards may vary by location; please refer to announcements from local governments. Generally, as wind strength increases and warning levels rise, corresponding social response measures are escalated. Do not rely on personal perception to judge wind strength; instead, closely monitor the latest official warning information.
Stay alert and take scientific precautions to minimize losses caused by typhoons. Real-time typhoon tracks can be queried at TyphoonSays (taifengshuo.com)
This article is typhoonsay's original copy content, and the local policy standards are based on the local government's latest release.