Beaufort Scale

bft

kn

m/s

km/h

classification

appearance of wind effects

0

0-1

0-0,2

0-1

calm

smoke rises vertically

1

1-3

0,3-1,5

1-5

light air

smoke drift indicates wind direction

2

4-6

1,6-3,3

6-11

light breeze

wind felt on face

3

7-10

3,4-5,4

12-19

gentle breeze

leaves are moving, light flags extended

4

11-15

5,5-7,9

20-28

moderate breeze

twigs are moving, flags extended

5

16-21

8,0-10,7

29-38

fresh breeze

small trees in leaf begin to sway

6

22-27

10,8-13,8

39-49

strong breeze

large tree branches moving, wind whistling in wires

7

28-33

13,9-17,1

50-61

near gale

smaller trees begin to sway, noticeably difficult to walk

8

34-40

17,2-20,7

62-74

gale

whole trees in motion, twigs are broken from trees, walking into the wind is very difficult

9

41-47

20,8-24,4

75-88

strong gale

slight structural damage occurs, slates blown off of roofs

10

48-55

24,5-28,4

89-102

storm

trees uprooted, considerable building damages

11

56-63

28,5-32,6

103-117

violent storm

widespread damage

12

64<

32,7<

118

hurricane

extreme destruction