Beaufort Scale

Beaufort scaleMean speed (knots)Description termState of SeaWave height (feet)
00CalmLike a mirror
12Light airsSlight ripple(1/3)
25Light breezeSmall wavelets(1/2)
39Gentle breezeLarge wavelets; Crests begin to break; a few white horses2
413Mod. breezeSmall waves; becoming longer; more frequent white horses3
519Fresh breezeModerate waves; longer form; some spray6
624Strong breezeLarge waves; White foam crests; extensive spray10
730Near galeSea heaps up; foam from breaking waves streaks along wind direction13
837GaleModerately high waves; foam in well marked streaks18
944Strong galeHigh waves; crests of waves tumble over; spray affects visibility23
1052StormVery high waves; great patches of white foam in wind; tumbling sea becomes heavy and shock-like. Visibility more affected29
1160Violent stormExceptionally high waves (medium sized ships lost from view behind waves) Sea covered with long white foam patches; bad visibility37
12oh shitHurricaneAir filled with foam and spray; sea completely white with driving spray; visibility very seriously affected.50 +