Bft MPH Km/h Knots Description
0 <1 <1 <0.54 Calm Sea : Like a mirror Near Land : Calm On Land : Smoke rises vertically Kiters : Grrrr... 1 1-3 1-5 0.54-2.97 Light Air Sea : Ripples with appearance of scales no foam crests Near Land : Small sailboat just has steerage way On Land : Smoke drift indicates wind direction vanes do not move 2 4-7 6-11 2.97-6.21 Light Sea : Small wavelets crests of glassy Breeze appearance, not breaking Near Land : Winds fill the sails of small boats which then travel at 1 - 2 knots On Land : Wind felt on face; leaves rustle vanes begin to move 3 8-12 12-19 6.21-10.53 Gentle Sea : Large wavelets; crests begin to break, Breeze scattered whitecaps Near Land : Sailboats begin to heel and travel at about 3-4 knots On Land : Leaves, small twigs in constant motion; light flags extended 4 13-18 20-28 10.53-15.39 Moderate Sea : Small waves 0.5 - 1.25 meters high, Breeze becoming longer; numerous whitecaps Near Land : Good working breeze, sailboats carry all sails with good heel On Land : Dust, leaves, and loose paper raised up; small branches move 5 19-24 29-38 15.39-20.79 Fresh Sea : Moderate waves of 1.25 - 2.5 m Breeze taking longer form; many whitecaps; some spray Near Land : Sailboarts shorten sail On Land : Small trees in leaf begin to sway Kiters : Probably too much wind for most people 6 25-31 39-49 20.79-26.73 Strong Sea : Larger waves 2.5 - 4 meters forming; Breeze whitecaps everywhere, more spray Near Land : Sailboats have double-reefed mailsails On Land : Larger branches of trees in motion; whistling heard in wires Kiters : Not for the weak of heart. 7 32-38 50-61 26.73-33.21 Near Sea : Sea heaps up, waves 4 - 6 m; Gale white foam from breaking waves begins to be blown in streaks Near Land : Boats remain in harbor; those at sea heave-to On Land : Whole trees in motion; resistance felt in walking against wind 8 39-46 62-74 33.21-40.23 Gale Sea : Moderately high (4 - 6 m) waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks Near Land : All boats make for harbor, if near On Land : Twigs and small branches broken off trees; progress generally impaired Kiters : Probably shouldn't be out 9 47-54 75-88 40.23-47.79 Strong Sea : High waves (6 m); sea begins Gale to roll; dense streaks of foam; spray may reduce visibility On Land : Slight structural damage occurs; slate blown from roofs Kiters : Get off the beach and take cover. 10 55-63 89-102 47.79-55.35 Storm Sea : Very high waves (6 - 9 m) with overhanging crests; sea takes a white appearance as foam is blown in very dense streaks; rolling is heavy and visibility is reduced On Land : Seldom experienced on land; Trees broken or uprooted; considerable damage occurs 11 64-72 103-117 55.35-63.44 Violent Sea : Exceptionally high (9-14 m) waves; Storm sea covered with white foam patches; visibility still more reduced On Land : Very rarely experienced on land; usually accompanied by widespread damage 12 73+ 118+ 63.44+ Hurricane Sea : Air filled with foam; waves over 14 meters; sea completly white with driving spray; visibility greatly reduced Kiters : Perfect time to try out that new stack of Flexi's. :-)
