Windsurfing Academy : Competition

Beaufort

Wind strength

Wind speed

Effect

km/h *

mph

Knots

0

CALM

0-1

0

Smoke rises vertically.

1

LIGHT AIR

1-5

1-3

0.8-2.6

Smoke drifts.

2

SLIGHT BREEZE

6-11

4-7

3.5-6.1

Leaves rustle, weather vanes move, wind felt on face

3

GENTLE BREEZE

12-19

8-12

7.0-10.4

Light flags unfurl, leaves and twigs on trees move steadily

4

MODERATE BREEZE

20-28

13-18

11.3-15.6

Small branches move, loose dust and paper fly about

5

FRESH BREEZE

29-38

19-24

16.5-20.9

Leafy shrubs and trees sway

6

STRONG BREEZE

39-49

25-31

21.7-26.9

Big branches move, wind pulls umbrellas

7

HIGH WIND

50-61

32-38

27.8-33.0

Trees sway, walkers push into the wind.

8

GALE

62-74

39-46

33.9-40.0

Twigs break off trees, walking is hard.

9

STRONG GALE

75-88

47-54

40.8-46.9

Shingles, slates, and branches are blown off. Slight building damage

10

STORM

89-102

55-63

47.8-54.7

Serious building damage trees uprooted

11

VIOLENT STORM

103-117

64-72

55.6-62.6

Widespread damage, wild storm.

12

HURRICANE >

117 KM/H >

73MPH >

63.4 Knots

Violent destruction of buildings & vehicles