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How windy is it?
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Beaufort scale number
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Descriptive term
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Units in km/h
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Units in knots
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Description on Land
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Description at Sea
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Calm
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Smoke rises vertically
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Sea like a mirror.
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1-3
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Light winds
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19 km/h or less
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10 knots or less
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Wind felt on face; leaves rustle; ordinary vanes moved by wind.
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Small wavelets, ripples formed but do not break: A glassy appearance maintained.
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Moderate winds
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20 – 29 km/h
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11-16 knots
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Raises dust and loose paper; small branches are moved.
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Small waves – becoming longer; fairly frequent white horses.
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Fresh winds
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30 – 39 km/h
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17-21 knots
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Small trees in leaf begin to sway; crested wavelets form on inland waters
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Moderate waves, taking a more pronounced long form; many white horses are formed – a chance of some spray
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Strong winds
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40 – 50 km/h
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22-27 knots
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Large branches in motion; whistling heard in telephone wires; umbrellas used with difficulty.
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Large waves begin to form; the white foam crests are more extensive with probably some spray
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Near gale
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51 – 62 km/h
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28-33 knots
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Whole trees in motion; inconvenience felt when walking against wind.
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Sea heaps up and white foam from breaking waves begins to be blown in streaks along direction of wind.
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Gale
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63 – 75 km/h
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34-40 knots
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Twigs break off trees; progress generally impeded.
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Moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks along the direction of the wind.
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Strong gale
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76 – 87 km/h
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41-47 knots
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Slight structural damage occurs -roofing dislodged; larger branches break off.
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High waves; dense streaks of foam; crests of waves begin to topple, tumble and roll over; spray may affect visibility.
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10
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Storm
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88 – 102 km/h
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48-55 knots
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Seldom experienced inland; trees uprooted; considerable structural damage.
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Very high waves with long overhanging crests; the resulting foam in great patches is blown in dense white streaks; the surface of the sea takes on a white appearance; the tumbling of the sea becomes heavy with visibility affected.
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11
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Violent storm
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103 -117 km/h
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56-63 knots
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Very rarely experienced – widespread damage
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Exceptionally high waves; small and medium sized ships occasionally lost from view behind waves; the sea is completely covered with long white patches of foam; the edges of wave crests are blown into froth.
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12+
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Hurricane
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118 km/h or more
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64 knots or more
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Very rarely experienced – widespread damage
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The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected
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(from the Australian Bureau of Meteorology)
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