Interesting Weather Facts   Go to the Weather Channel The Beaufort scale is an empirical measure for describing wind intensity based mainly on observed sea conditions. Its full name is the Beaufort wind force scale. Wind Speed  -  Bft. > Beaufort Bft. English Wind Speed Dutch Norwegian French German knots km/h m/s 0 calm 0-1 0-1 0-0.2 windstil stille calme Stille 1 light air 1-3 1-5 0.3-1.5 zwak flau vind très légère brise leiser Zug 2 light breeze 4-6 6-11 1.6-3.3 zwak svak bris légère brise leichte Brise 3 gentle breeze 7-10 12-19 3.4-5.4 matig lett bris petite brise schwache Brise 4 moderate breeze 11-16 20-28 5.5-7.9 matig laber bris jolie brise mäßige Brise 5 fresh breeze 17-21 29-38 8.0-10.7 vrij krachtig frisk bris bonne brise frische Brise 6 strong breeze 22-27 39-49 10.8-13.8 krachtig liten kuling vent frais starker Wind 7 near gale 28-33 50-61 13.9-17.1 hard stiv kuling grand frais steifer Wind 8 gale 34-40 62-74 17.2-20.7 stormachtig sterk kuling coup de vent stürmischer Wind 9 strong gale 41-47 75-88 20.8-24.4 storm liten storm fort coup de vent Sturm 10 storm 48-55 89-102 24.5-28.4 zware storm full storm tempète schwerer Sturm 11 violent storm 56-63 103-117 28.5-32.6 zeer zware storm sterk storm violente tempète orkanartiger Sturm 12 hurricane > 63 > 117 > 32.6 orkaan orkan ouragan Orkan Bft. Wind Speed Wave Height * Sea Conditions Land Conditions knots km/h mph m/s m ft 0 0 0 0 0-0.2 0 0 Flat. Calm. Smoke rises vertically. 1 1-3 1-6 1-3 0.3-1.5 0.1 0.33 Ripples without crests. Wind motion visible in smoke. 2 4-6 7-11 4-7 1.6-3.3 0.2 0.66 Small wavelets. Crests of glassy appearance, not breaking Wind felt on exposed skin. Leaves rustle. 3 7-10 12-19 8-12 3.4-5.4 0.6 2 Large wavelets. Crests begin to break; scattered whitecaps Leaves and smaller twigs in constant motion. 4 11-16 20-29 13-18 5.5-7.9 1 3.3 Small waves. Dust and loose paper raised. Small branches begin to move. 5 17-21 30-39 19-24 8.0-10.7 2 6.6 Moderate (1.2 m) longer waves. Some foam and spray. Smaller trees sway. 6 22-27 40-50 25-31 10.8-13.8 3 9.9 Large waves with foam crests and some spray. Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. 7 28-33 51-62 32-38 13.9-17.1 4 13.1 Sea heaps up and foam begins to streak. Whole trees in motion. Effort to walk against the wind. 8 34-40 63-75 39-46 17.2-20.7 5.5 18 Moderately high waves with breaking crests forming spindrift. Streaks of foam. Twigs broken from trees. Cars veer on road. 9 41-47 76-87 47-54 20.8-24.4 7 23 High waves (2.75 m) with dense foam. Wave crests start to roll over. Considerable spray. Light structure damage. 10 48-55 88-102 55-63 24.5-28.4 9 29.5 Very high waves. The sea surface is white and there is considerable tumbling. Visibility is reduced. Trees uprooted. Considerable structural damage. 11 56-63 103-117 64-72 28.5-32.6 11.5 37.7 Exceptionally high waves. Widespread structural damage. 12 > 63 > 117 > 72 > 32.7 14 + 46 + Huge waves. Air filled with foam and spray. Sea completely white with driving spray. Visibility very greatly reduced. Massive and widespread damage to structures.    * Note that wave heights in the scale are for conditions in the open ocean, not along shore. Travel-Island.com 2004, 2008 . Travel Forum . Travel Photo Albums . Weather Channel