number |
[knots] |
[mph] |
[m/s] |
Height [feet] |
Height [meters] |
|||
| under 1 | under 1 | 0.0 - 0.2 | ~0 | ~0 | Calm | Sea like mirror. | Calm; smoke rises vertically. | |
| 1 - 3 | 1 - 3 | 0.3 - 1.5 | 0.25 | 0.1 | Light air | Ripples with appearance of scales; no foam crests. | Direction of wind shown by smoke drift but not by wind vanes. | |
| 4 - 6 | 4 - 7 | 1.6 - 3.3 | 0.5 - 1.0 | 0.2 - 0.3 | Light breeze | Small wavelets; crests of glassy appearance, not breaking. | Wind felt on face; leaves rustle; vanes moved by wind. | |
| 7 - 10 | 8 - 12 | 3.4 - 5.4 | 2.0 - 3.0 | 0.6 - 1.0 | Gentle breeze | Large wavelets; crests begin to break; scattered whitecaps. | Leaves and small twigs in constant motion; wind extends light flag. | |
| 11 - 16 | 13 - 18 | 5.5 - 7.9 | 3.5 - 5.0 | 1.0 - 1.5 | Moderate breeze | Small waves, becoming longer; numerous whitecaps. | Raises dust and loose paper; small branches are moved. | |
| 17 - 21 | 19 - 24 | 8.0 - 10.7 | 6.0 - 8.0 | 2 - 2.5 | Fresh breeze | Moderate waves, taking longer form; many whitecaps; some spray. | Small trees in leaf begin to sway; crested wavelets form on inland waters. | |
| 22 - 27 | 25 - 31 | 10.8 - 13.8 | 9.5 - 13.0 | 3.0 - 4.0 | Strong breeze | Larger waves forming; whitecaps everywhere; more spray. | Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty. | |
| 28 - 33 | 32 - 38 | 13.9 - 17.1 | 13.5 - 19.0 | 4.0 - 5.5 | Near gale | Sea heaps up; white foam from breaking waves begin to be blown in streaks. | Whole trees in motion; inconvenience felt when walking against the wind. | |
| 34 - 40 | 39 - 46 | 17.2 - 20.7 | 18.0 - 25.0 | 5.5 - 7.5 | Gale | Moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks. | Breaks twigs off trees; generally impedes progress. | |
| 41 - 47 | 47 - 54 | 20.8 - 24.4 | 23.0 - 32.0 | 7.0 - 10.0 | Strong gale | High waves; sea begins to roll; dense streaks of foam; spray may reduce visibility. | Slight structural damage occurs. | |
| 48 - 55 | 55 - 63 | 24.5 - 28.4 | 29.0 - 41.0 | 9.0 - 12.5 | Storm | Very high waves with overhanging crests; sea takes white appearance as foam is blown in very dense streaks; rolling is heavy and visibility reduced. | Trees uprooted; considerable structural damage occurs. | |
| 56 - 63 | 64 - 72 | 28.5 - 32.6 | 37.0 - 52.0 | 11.5 - 16.0 | Violent storm | Exceptionally high waves; sea covered with white foam patches; visibility still more reduced. | Accompanied by widespread damage. | |
| 64 and over | 73 and over | 32.7 and over | 45 and over | 14 and over | Hurricane | Air filled with foam; sea completely white with driving spray; visibility greatly reduced. | Accompanied by widespread damage. |
Guide to Sea State, Wind, and Clouds. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service.
Air Force Manual 15-111: Surface Weather Observations. Department of the Air Force, 1 November 1998.
An alternative Beaufort scale is here.