Wind speed conversion table (at 10 metres above ground)
Beaufort scale | Range of wind speeds | Mean wind speed | |||||||
---|---|---|---|---|---|---|---|---|---|
knots | m s−1 | km h−1 | miles h−1 | knots | m s−1 | km h−1 | miles h−1 | ||
0 | Calm | < 1 | 0.0 – 0.2 | < 1 | < 1 | 0 | 0.0 | 0 | 0 |
1 | Light air | 1 – 3 | 0.3 – 1.5 | 1 – 5 | 1 – 3 | 2 | 0.9 | 3 | 2 |
2 | Light breeze | 4 – 6 | 1.6 – 3.3 | 6 – 11 | 4 – 7 | 5 | 2.4 | 9 | 5 |
3 | Gentle breeze | 7 – 10 | 3.4 – 5.4 | 12 – 19 | 8 – 12 | 9 | 4.4 | 16 | 10 |
4 | Moderate breeze | 11 – 16 | 5.5 – 7.9 | 20 – 28 | 13 – 18 | 13 | 6.7 | 24 | 15 |
5 | Fresh breeze | 17 – 21 | 8.0 – 10.7 | 29 – 38 | 19 – 24 | 18 | 9.3 | 34 | 21 |
6 | Strong breeze | 22 – 27 | 10.8 – 13.8 | 39 – 49 | 25 – 31 | 24 | 12.3 | 44 | 28 |
7 | Near gale | 28 – 33 | 13.9 – 17.1 | 50 – 61 | 32 – 38 | 30 | 15.5 | 55 | 35 |
8 | Gale | 34 – 40 | 17.2 – 20.7 | 62 – 74 | 39 – 46 | 37 | 18.9 | 68 | 42 |
9 | Strong gale | 41 – 47 | 20.8 – 24.4 | 75 – 88 | 47 – 54 | 44 | 22.6 | 82 | 50 |
10 | Storm | 48 – 55 | 24.5 – 28.4 | 89 – 102 | 55 – 63 | 52 | 26.4 | 96 | 59 |
11 | Violent Storm | 56 – 63 | 28.5 – 32.6 | 103 – 117 | 64 – 72 | 60 | 30.5 | 110 | 68 |
12 | Hurricane | 64 – 71 | 32.7 – 36.9 | 118 – 133 | 73 – 82 | 68 | 34.8 | 125 | 78 |