Beaufort Force	Description	Specification on Land	Sea State	knots	mph	kph
0	Calm	Smoke rises vertically	Sea like a mirror	<1	<1	<1
1	Very Light	Direction of wind shown by smoke drift but not by wind vanes.	Ripples with appearace of scales, no foam crests	1-3	1-3	1-5
2	Light breeze	Wind felt on face, leaves rustle, ordinary wind vane moved by wind.	Wavelets, small but pronounced. Crests with glassy appearance, but do not break	4-6	4-7	6-11
3	Gentle Breeze	Leaves and small twigs in constant motion, wind extends white flag.	Large Wavelets, crests begin to break. Glassy looking foam, occasional white horses.	7-10	8-12	12-19
4	Moderate breeze	Wind raises dust and loose paper, small branches move.	Small waves becoming longer, frequent white horses.	11-16	13-18	20-29
5	Fresh breeze	Small trees in leaf start to sway, crested wavelets on inland waters.	Moderate waves of pronounced long form. Many white horses, some spray.	17-21	19-24	30-39
6	Strong breeze	Large branches in motion, whistling in telegraph wires, umbrellas used with difficulty.	Some large waves, extensive white foam crests, some spray.	22-27	25-31	40-50
7	Near gale	Whole trees in motion, inconvenient to walk against wind	Sea heaped up, white foam from breaking waves blowing in streaks with the wind.	28-33	32-38	51-61
8	Gale	Twigs break from trees, difficult to walk.	Moderately high and long waves. Crests break into spin drift, blowing foam in well marked streaks.	34-40	39-46	62-74
9	Strong gale	Slight structural damage occurs, chimney pots and slates removed.	High waves, dense foam streaks in wind, wave crests topple, tumbe and roll over. Spray reduces visibility.	41-47	47-54	75-87
10	Storm	Trees uprooted, considerable structural damage occurs.	Very high waves with long overhanging crests. Dense blowing foam, sea surface appeas white. Heavy tumbling of sea, shocklike, poor visibility.	48-55	55-63	88-101
11	Violent storm	Widespread damage.	Exceptionally high waves, sometimes concealing small and medium sized ships.	56-63	64-73	102-117
12	Hurricane	Widespread damage	Air filled with foam and spray, sea white with driving spray.	>64	>74	>119