Beaufort Wind Scale

Beaufort Number	Descriptive Term	Speed in Knots	Effects on Open Waters
0	Calm	0	Sea like a mirror
1	Light Air	1 to 3	Ripples with the appearance of scales are formed, without foam crests
2	Light Breeze	4 to 6	Small wavelets, still short, but more pronounced; crests have a glassy appearance but do not break
3	Gentle	7 to 10	Large wavelets; crests begin to break; foam of glassy appearance, perhaps scattered white horses (white caps)
4	Moderate	11 to 16	Small waves, becoming longer; fairly frequent white horses
5	Fresh	17 to 21	Moderate waves, taking a more pronounced long form; many white horses are formed (chance of some spray)
6	Strong	22 to 27	Large waves begin to form; the white foam crests are more extensive everywhere (probably some spray)
7	Near Gale	28 to 33	Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind
8	Gale	34 to 40	Moderately high waves of greater length; edges of crests begin to break into the spindrift; the foam is blown in well-marked streaks along the direction of the wind
9	Strong Gale	41 to 47	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
10	Storm	48 to 55	Very high waves with long overhanging crests; the resulting foam, in great patches, is blown in dense white streaks along the direction of the wind; on the whole, the sea surface takes a white appearance; the tumbling of the sea becomes heavy and shock-like; visibility affected
11	Violent	56 to 63	Exceptionally high waves (small and medium size 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; everywhere the edges of the wave crests are blown into froth; visibility affected
12	Hurricane	64 and over	The air is filled with foam and spray; sea completely white with driving spray; visibility very seriously affected

Statute Mile = 5,280 feet

Nautical Mile = 6,076.11549... feet in length (The length of the nautical mile is very close to the mean value of the length of 1 minute of latitude)

To convert wind speeds in knots to statute miles per hour - Speed in Knots X 1.15

To convert wind speeds in statute miles per hour to knots - Speed in MPH X 0.868