Wind Speed Table

KnotsBeaufortm/skm/hmphLabelEffect on seaEffects on land
< 100 – 0.2<1<1CalmSea like a mirrorCalm. Smoke rises vertically.
1-310.3-1.51-51-3Light AirRipples with the appearance of scales are formed, but without foam crestsWind motion visible in smoke.
4-621.6-3.36-114-7Light BreezeSmall wavelets, still short, but more pronounced. Crests have a glassy appearance and do not breakWind felt on exposed skin. Leaves rustle.
7-1033.4-5.412-198-12Gentle BreezeLarge wavelets. Crests begin to break. Foam of glassy appearance.Perhaps scattered white horsesLeaves and smaller twigs in constant motion.
11-1545.5-7.920-2813-17Moderate BreezeSmall waves, becoming larger; fairly frequent white horsesDust and loose paper raised. Small branches begin to move.
16-2158.0-10.729-3818-24Fresh BreezeModerate waves, taking a more pronounced long form; many white horses are formed. Chance of some sprayBranches of a moderate size move. Small trees begin to sway.
22-27610.8-13.839-4925-30strong BreezeLarge waves begin to form; the white foam crests are more extensive everywhere. Probably some sprayLarge branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic garbage cans tip over.
28-33713.9-17.150-6131-38Near GaleSea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the windWhole trees in motion. Effort needed to walk against the wind. Swaying of skyscrapers may be felt, especially by people on upper floors.
34-40817.2-20.762-7439-46GaleModerately high waves of greater length; edges of crests begin to break into spindrift. The foam is blown in well-marked streaks along the direction of the windTwigs broken from trees. Cars veer on road.
41-47920.8-24.475-8847-54Severe GaleHigh waves. Dense streaks of foam along the direction of the wind. Crests of waves begin to topple, tumble and roll over. Spray may affect visibilityLarger branches break off trees, and some small trees blow over.Construction/temporary signs and barricades blow over. Damage to circus tents and canopies.
48-551024.5-28.489-10255-63StormVery high waves with long over-hanging crests. The resulting foam, in great patches, is blown in dense white streaks along the direction of the wind. On the whole the surface of the sea takes on a white appearance.The ‘tumbling’ of the sea becomes heavy and shock-like. Visibility affectedTrees are broken off or uprooted, saplings bent and deformed, poorly attached asphalt shingles and shingles in poor condition peel off roofs.
56-631128.5-32.6103-11764-73Violent StormExceptionally high waves (small and medium-size ships might disappear behind the waves). The sea is completely covered with long white patches of foam flying along the direction of the wind. Everywhere the edges of the wave crests are blown into froth. Visibility affectedWidespread vegetation damage. More damage to most roofing surfaces, asphalt tiles that have curled up and/or fractured due to age may break away completely.
64-7112>32.7>118>74HurricaneThe air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affectedConsiderable and widespread damage to vegetation, a few windows broken, structural damage to mobile homes and poorly constructed sheds and barns. Debris may be hurled about.