Beaufort Wind Scale

Beaufort

Avg m/s

Avg km/h

Avg Knots

Surroundings

0 (calm)

 0

0

0-1

Smoke rises vertically and the see is mirror smooth

1 (light air)

0.5-1.3

2-5

1-3

Smokes moves slightly with breeze and  shows direction of wind

2 (light breeze)

1.4-3.3

6 12

4-6

You can feel wind on your face and hear the leaves start to rustle

3 (gentle breeze)

3.4-5.5

13 20

7-10

Smoke will move horizontally and small branches start to sway. Wind extends a light flag

4 (moderate breeze)

5.6-8.3

21 30

11-16

Loose dust or sand on the ground will move and larger branches will sway, loose paper blows around, and fairly frequent whitecaps occur

5 (fresh breeze)

8.4-11.1

31 40

17-21

Surface waves form on water and small trees sway

6 (strong breeze)

11.2-13.9

41 - 50

22-27

Trees begin to bend with the force of the wind and causes whistling in telephone wires and some spray on the sea surface

7 (moderate gale)

14.0-16.9

51-61

28-33

large trees sway

8 (fresh gale) 

17.0-20.5

62-74

34-40

twigs break from trees, and long streaks of foam appear on the ocean

9 (strong gale)

20.6-24.7

75-89

41-47

branches break from trees

10 (whole gale) 

24.8-28.6

90-103

48-55

trees are uprooted, and the sea takes on a white appearance

11 (storm)

28.7-33.0

104-119

56-63

widespread damage

12 (hurricane)

33.0+

120+

64+

structural damage on land and storm waves at sea

 

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