How Fast Is Strong Wind? Beaufort Scale (km/h and mph)
Wind counts as strong from 50 km/h, force 7 on the Beaufort scale, a “near gale” (50–61 km/h, 32–38 mph): whole trees move and walking against the wind takes effort. From 39 km/h (force 6, a “strong breeze”) it is already noticeable and annoying: large branches move and umbrellas are hard to use. From 62 km/h (force 8) it is a gale. These are the standard WMO (World Meteorological Organization) ranges, and they describe the mean wind, not gusts.
Beaufort scale table: km/h, mph, force and effects
Mean wind speeds (10-minute average at 10 meters above ground), using the standard WMO ranges.
| Force | Name | km/h | mph | Knots | Effects on land |
|---|---|---|---|---|---|
| 0 | Calm | <1 | <1 | <1 | Smoke rises vertically. |
| 1 | Light air | 1–5 | 1–3 | 1–3 | Smoke drifts, but wind vanes do not move. |
| 2 | Light breeze | 6–11 | 4–7 | 4–6 | Felt on the face; leaves rustle and wind vanes move. |
| 3 | Gentle breeze | 12–19 | 8–12 | 7–10 | Leaves and small twigs in constant motion; light flags extend. |
| 4 | Moderate breeze | 20–28 | 13–18 | 11–16 | Raises dust and loose paper; small branches move. |
| 5 | Fresh breeze | 29–38 | 19–24 | 17–21 | Small leafy trees sway; small wavelets form on lakes. |
| 6 | Strong breeze | 39–49 | 25–31 | 22–27 | Large branches move; wires whistle; umbrellas are hard to use. |
| 7 | Near gale | 50–61 | 32–38 | 28–33 | Whole trees move; walking against the wind takes effort. |
| 8 | Gale | 62–74 | 39–46 | 34–40 | Twigs and branches break; walking is very difficult. |
| 9 | Strong gale | 75–88 | 47–54 | 41–47 | Slight damage to buildings: roof tiles and antennas are torn off. |
| 10 | Storm | 89–102 | 55–63 | 48–55 | Rare inland: trees are uprooted and structures are badly damaged. |
| 11 | Violent storm | 103–117 | 64–72 | 56–63 | Rarely experienced on land: widespread damage. |
| 12 | Hurricane force | ≥118 | ≥73 | ≥64 | Devastation. |
Names differ between languages: in English, force 6 is a “strong breeze” and force 7 a “near gale,” while in Spanish or Portuguese “strong wind” is force 7. That is why it is best to go by the km/h. To convert units: m/s × 3.6 = km/h; knots × 1.852 = km/h; mph × 1.609 = km/h. The range in each unit is rounded separately, so a conversion can differ by one unit from the table.
At what speed does wind become a nuisance or cause damage?
There is no single threshold: it depends on what you are doing. As a reference, according to the table:
- From 39 km/h (force 6): annoying to walk in and umbrellas become useless; large branches move.
- From 50 km/h (force 7): walking against the wind takes effort; watch out for loose objects and tall vehicles.
- From 62 km/h (force 8): branches break and walking is very difficult; it is best to avoid outdoor activities.
- From 75 km/h (force 9): slight damage to roofs and antennas begins.
- From 89 km/h (force 10): trees can come down and structures are badly damaged.
Wind on the farm and in the city
On the farm, wind limits specific jobs: good spraying practice usually advises against applying products in winds above about 15 km/h (9 mph) (always check the product label and local rules), and sprinkler irrigation becomes uneven in strong wind. There are also regional winds, such as the sudestada on the Río de la Plata, which combines southeasterly wind with a rising river (more in Sudestada in Buenos Aires).
Strong wind alerts in Contingencias
Vigía, the alerts feature of Contingencias Premium, includes a “Strong wind” alert. It is based on forecast gusts (not the mean wind of the Beaufort scale) and warns you up to two days ahead when gusts are expected to exceed a threshold. The starting threshold is your city's own — calculated from your city's gust forecasts, with a minimum of 30 km/h — and you can adjust it. It relies on forecasts, which can change; for official warnings, check your national weather service. Learn about Vigía.
Frequently asked questions
How many km/h is strong wind?
From 50 km/h (force 7, a “near gale” in English terms and “strong wind” in Spanish, Italian and Portuguese). From 39 km/h (force 6, “strong breeze”) it is already noticeable and annoying. From 62 km/h (force 8) it is a gale.
Is a wind of 10, 13 or 20 km/h a lot?
No. 10 km/h is force 2 and 13 km/h is force 3 (leaves and small twigs in constant motion); 20 km/h is force 4 and raises dust and loose paper. None of them counts as strong wind.
Is 50 km/h a strong wind?
Yes. 50 km/h is the start of force 7 (50–61 km/h): whole trees move and walking against the wind takes effort.
What is the difference between wind and a gust?
The Beaufort scale uses the mean wind, averaged over several minutes. A gust is a brief peak lasting seconds and can be well above the mean wind; that is why a forecast may say, for example, wind of 35 km/h with gusts of 55 km/h.
Does the Beaufort scale stop at 12?
The original scale runs from 0 to 12 (force 12, hurricane, starts at 118 km/h). Some weather services in Asia use an extended version up to 17 for typhoons.
How can I estimate wind without an anemometer?
Watch the smoke, leaves and branches and compare them with the effects column of the table. It is a rough estimate, but it is enough to place yourself on the scale.
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