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Beaufort wind scale

Force Description Wind (kts) Waves (m) Sea state
0 calm 0-1 kt 0 m Sea like a mirror sea beaufort 1
1 Light airs 1-3 kts 0.1 m Ripples with the appearance of scales are formed, but without foam crests. sea beaufort 1
2 Light breeze 4-6 kts 0.2 m Small wavelets, still short, but more pronounced. Crests have a glassy appearance and do not break. sea beaufort 2
3 Gentle breeze 7-10 kts 0.6 m Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses. sea beaufort 3
4 Moderate breeze 11-16 kts 1 m Small waves, becoming larger; fairly frequent white horses. sea beaufort 4
5 Fresh breeze 17-21 kts 2 m Moderate waves, taking a more pronounced long form; many white horses are formed. Chance of some spray. sea beaufort 5
6 StrongBreeze 22-27 kts 3 m Large waves begin to form; the white foam crests are more extensive everywhere. Probably some spray. sea beaufort 6
7 Near gale 28-33 kts 4 m Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind. sea beaufort 7
8 Gale 34-40 kts 5.5 m Moderately high waves of greater length; edges of crests begin to break into spindrift. The foam is blown in well-marked streaks long the direction of the wind. sea beaufort 8
9 Severe gale 41-47 kts 7 m High waves. Dense streaks of foam along the direction of the wind. Crests of waves begin to topple, tumble and roll over. Spray may affect visibility. sea beaufort 9
10 Storm 48-55 kts 9 m Very 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 affected. sea beaufort 10
11 Violent Storm 56-63 kts 11.5 m Exceptionally high waves (small and medium-size ships might be for a time lost to view behind the waves). The sea is completely covered with long white patches of foam lying along the direction of the wind. Everywhere the edges of the wave crests are blown into froth. Visibility affected. sea beaufort 11
12 Hurricane 64-71 kts >14 m The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected. sea beaufort 12

This page last updated: 6 March 2019