Beaufort Scale (wind)



Force Description Sea State Description Speed Knots Range Forecast Description Sea State Waves metres
0 Calm Sea like a mirror 0 <1 Calm Calm 0
1 Light air “Ripples with the appearance of scales are formed but without foam crests.” 2 1-3 Light Smooth 0.1
2 Light breeze “Small wavelets still short but more pronounced. Crests have a glassy appearance and do not break.” 5 4-6 Light Smooth 0.2
3 Gentle breeze Large wavelets. Crests begin to break. Foam of glassy appearance. Scattered white horses. 9 7-10 Light Slight 0.6
4 Moderate breeze “Small waves becoming longer fairly frequent white horses.” 13 11-16 Moderate Moderate 1
5 Fresh breeze “Moderate waves taking a more Pronounced long form; many white horses are formed. Chance of some spray.” 19 17-21 Fresh Rough 2
6 Strong breeze Large waves begin to form; white foam crests are more extensive everywhere. Probably some spray. 24 22-27 Strong Very rough 3
7 Near gale Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind. 30 28-33 Strong High 4
8 Gale Moderately 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 wind. 37 34-40 Gale Very high 5.5
9 Strong gale “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.” 44 41-47 Severe gale Very high 7
10 Storm “Very high waves with long over-hanging crests. The resulting foam in great patches is blown in dense white streaks along the direction of wind. On the whole the surface of the sea takes a white appearance. The ‘tumbling’ of the sea becomes heavy and shock-like. Visibility is affected” 52 48-55 Storm Phenomenal 9
11 Violent storm Exceptionally high waves (small & medium sized ships might be lost to view for a time behind the waves). The sea is completely covered with long white patches of foam lying along the direction of the wind. Every-where the edges of the wave crests are blown into froth. Visibility is affected. 60 56-63 Violent storm Phenomenal 11.5
12 Hurricane The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected 64+ Hurricane 14

Sub Aqua Club