The Beaufort scale of wind speeds is a convenient way of referring to approximate wind speeds and is often used in weather and shipping forecasts. Originally developed for use at sea it has been modified for use on land. |
The Beaufort Scale for use at sea
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for Land Scale)
| Beaufort Force | Description | Sea State | Speed | ||
| knots | km/h | mph | |||
| 0 | Calm | Sea like a mirror | Less than 1 | Less than 1 | Less than 1 |
| 1 | Very Light | Ripples with appearance of scales, no form crests | 1 - 3 | 1 - 5 | 1 - 3 |
| 2 | Light breeze | Wavelets, small but pronounced. Crests with glassy appearance, but do not break. | 4 -6 | 6 - 11 | 4 -7 |
| 3 | Gentle breeze | Large wavelets, crests begin to break. Glassy looking foam, occasional white horses. | 7 - 10 | 12 - 19 | 8 - 12 |
| 4 | Moderate breeze | Small waves becoming longer, frequent white horses. | 11 - 16 | 20 - 29 | 13 - 18 |
| 5 | Fresh breeze | Moderate waves of pronounced long form. Many whit horses, some spray. | 17 - 21 | 30 - 39 | 19 - 24 |
| 6 | Strong breeze | Some large waves, extensive white foam crests, some spray. | 22 - 27 | 40 - 50 | 25 - 31 |
| 7 | Near gale | Sea heaped up, white foam from breaking waves blowing in streaks with the wind. | 28 - 33 | 51 - 61 | 32 - 38 |
| 8 | Gale | Moderately high and long waves. Crests break into spin drift, blowing foam in well marked streaks. | 34 - 40 | 62 - 74 | 39 - 46 |
| 9 | Strong gale | High waves, dense foam streaks in wind, wave crests topple, tumble and roll over. Spray reduces visability. | 41 - 47 | 75 - 87 | 47 - 54 |
| 10 | Storm | Very high waves with long overhanging crests. Dence blowing foam, sea surface appears white. Heavy tumbling of sea, shock-like, poor visability. | 48 - 55 | 88 - 101 | 55 - 63 |
| 11 | Violent storm | Exceptionally high waves, sometimes concealing small and medium sized ships. Sea comletely covered with long white patches of foam. Edges of wave crests blown into froth . Poor visability. | 56 - 63 | 102 - 117 | 64 - 73 |
| 12 | Hurricane | Air filled with foam and spray, sea white with driving spray, visability. | >64 | >119 | >74 |
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The Beaufort Scale, adapted for use on land
(Click here for
Sea Scale)
| Beaufort Force | Description | Specification on land | Speed | ||
| knots | km/h | mph | |||
| 0 | Calm | Smoke rises vertically. | Less than 1 | Less than 1 | Less than 1 |
| 1 | Very Light | Direction of wind shown by smoke drift but not by wind vanes. | 1 - 3 | 1 - 5 | 1 - 3 |
| 2 | Light breeze | Wind felt on face , leaves rustle, ordinaryt wind vane moved by wind. | 4 - 6 | 6 - 11 | 4 - 7 |
| 3 | Gentle breeze | Leaves and small twigs in constant motion, wind extends white flag. | 7 - 10 | 12 - 19 | 8 - 12 |
| 4 | Moderate breeze | Wind raises dust and loose paper, small branches move. | 11 - 16 | 20 -29 | 13 - 18 |
| 5 | Fresh breeze | Small trees in leaf start to sway, crested wavelets on inland waters. | 17 - 21 | 30 39 | 19 - 24 |
| 6 | Strong breeze | Large branches in motion, whistling in telegraph wires, umberellas used with difficulty. | 22 - 27 | 40 - 50 | 25 - 31 |
| 7 | Near gale | Whole trees in motion, inconvient to walk against wind. | 28 - 33 | 51 - 61 | 32 - 38 |
| 8 | Gale | Twigs break from trees, difficult to walk. | 34 - 40 | 62 - 74 | 39 - 46 |
| 9 | Strong gale | Slight structural damage occuers, chimney pots and slates removed. | 41 - 47 | 75 - 87 | 47 - 54 |
| 10 | Storm | Trees uprooted, considerable structural damage occurs. | 48 - 55 | 88 - 101 | 55 - 63 |
| 11 | Violent storm | Widespread damage. | 56 - 63 | 102 - 117 | 64 - 73 |
| 12 | Hurricane | Widespread damage. | >64 | >119 | >74 |