Weather

Beaufort scale
0.3 Meters per second 0.3  to 1.5
Meters per second
Kilometres per hour
Miles per hour
Knots
1.6  to 3.4
Meters per second
Kilometres per hour
Miles per hour
Knots
1 Kilometres per hour 1.1  to  5.5 5.6  to 11
1 Miles per hour 1 to 3 4 to 7
1 Knots 1 to 2 3 to 6
3.4  to  5.4 Meters per second 5.5  to  7.9
Meters per second
Kilometres per hour
Miles per hour
Knots
8  to  10.7
Meters per second
Kilometres per hour
Miles per hour
Knots
12  to  19 Kilometres per hour 20  to  28 29  to 38
8  to  12 Miles per hour 13  to   17 18  to  24
7  to 10 Knots 11  to  15 16  to  20
10.8  to  13.8 Meters per second 13.9  to  17.1
Meters per second
Kilometres per hour
Miles per hour
Knots
17.2  to  20.7
Meters per second
Kilometres per hour
Miles per hour
Knots
39  to  49 Kilometres per hour 50  to  61 62  to  74
25  to  30 Miles per hour 31  to 38 39  to 46
21  to  26 Knots 27  to 33 34  to  40
20.8  to  24.4 Meters per second 24.6  to  28.4
Meters per second
Kilometres per hour
Miles per hour
Knots
28.5  to  32.6
Meters per second
Kilometres per hour
Miles per hour
Knots
75  to 88 Kilometres per hour 89  to  102 103  to  117
47  to 54 Miles per hour 55  to  63 64  to  72
41 to  47 Knots 48  to  55 56  to  73

greater than 32.7
Meters per second
Kilometres per hour
Miles per hour
Knots
greater than 118
greater than 73
greater than 64

Scale

Description

Km/h

Knots

Description on Land

Description at Sea

0

Calm

0

0

Smoke rises vertically

Sea like a mirror.

1-3

Light winds

19 km/h or less

10 knots or less

Wind felt on face; leaves rustle; ordinary vanes moved by wind.

Small wavelets, ripples formed but do not break: A glassy appearance maintained. 

4

Moderate winds

20 - 30 km/h

11-16 knots

Raises dust and loose paper; small branches are moved.

Small waves - becoming longer; fairly frequent white horses.

5

Fresh winds

31 - 39 km/h

17-21 knots

Small trees in leaf begin to sway; crested wavelets form on inland waters

Moderate waves, taking a more pronounced long form; many white horses are formed - a chance of some spray

6

Strong winds

41 - 50 km/h

22-27 knots

Large branches in motion; whistling heard in telephone wires; umbrellas used with difficulty. 

Large waves begin to form; the white foam crests are more extensive with probably some spray

7

Near gale

52 - 61 km/h

28-33 knots

Whole trees in motion; inconvenience felt when walking against wind.

Sea heaps up and white foam from breaking waves begins to be blown in streaks along direction of wind.

8

Gale

63 - 74 km/h

34-40 knots

Twigs break off trees; progress generally impeded.

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.

9

Strong gale

76 - 87 km/h

41-47 knots

Slight structural damage occurs -roofing dislodged; larger branches break off.

High waves; dense streaks of foam; crests of waves begin to topple, tumble and roll over; spray may affect visibility.

10

Storm

89 - 102 km/h

48-55 knots

Seldom experienced inland; trees uprooted; considerable structural damage.

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. 

11

Violent storm

104 -117 km/h

56-63 knots

Very rarely experienced - widespread damage

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.

12+

Cyclone

119 km/h or more

64 knots or more

The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected