Beaufort Wind Scale

A comprehensive guide to wind speed and sea conditions.

Beaufort Number	Description	Wind Speed (kts)	Sea Conditions
0	Calm	0-1	Sea like a mirror.
1	Light Air	1-3	Ripples with the appearance of scales are formed, but without foam crests.
2	Light Breeze	4-6	Small wavelets, still short, but more pronounced. Crests have a glassy appearance and do not break.
3	Gentle Breeze	7-10	Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses.
4	Moderate Breeze	11-16	Small waves, becoming larger; fairly frequent white horses.
5	Fresh Breeze	17-21	Moderate waves, taking a more pronounced long form; many white horses are formed.
6	Strong Breeze	22-27	Large waves begin to form (8-13 ft); the white foam crests are more extensive everywhere. Whitecaps common, more spray.
7	Near Gale	28-33	Sea heaps up (waves 13-20 ft) and white foam from breaking waves begins to be blown in streaks along the direction of the wind. White foam streaks off breakers.
8	Gale Force	34-40	Moderately high waves (13-20 ft) of greater length; edges of crests begin to break into spindrift. The foam is blown in well-marked streaks.
9	Strong Gale	41-47	High waves (20 ft). Dense streaks of foam. Crests of waves begin to topple, tumble and roll over. Sea begins to roll. Spray may affect visibility.
10	Storm Force	48-55	Very high waves (20-30 ft) with long overhanging crests. The sea takes on a white appearance. Heavy, shock-like tumbling. Visibility affected.
11	Violent Storm	56-63	Exceptionally high waves (30-45 ft). The sea is completely covered with long white patches of foam. Visibility affected.
12	Hurricane	64+	Air filled with foam and spray. Sea completely white with driving spray (waves over 45 ft). Visibility very seriously reduced.

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Beaufort Scale