Beaufort
number

Description term

Wind speeds

Wave height (m)

Wind

Wave

knots

m/s

probable

maximum

0

Calm

-

< 1

0 - 0.2

-

-

1

Light air

Ripples

1 - 3

0.3 - 1.5

0.1

0.1

2

Light breeze

Small wavelets

4 - 6

1.6 - 3.3

0.2

0.3

3

Gentle breeze

Large wavelets

7 - 10

3.4 - 5.4

0.6

1.0

4

Moderate breeze

Small waves

11 - 16

5.5 - 7.9

1.0

1.5

5

Fresh breeze

Moderate waves

17 - 21

8.0 - 10.7

2.0

2.5

6

Strong breeze

Large waves

22 - 27

10.8 - 13.8

3.0

4.0

7

Near gale

Large waves

28 - 33

13.9 - 17.1

4.0

5.5

8

Gale

Moderately high waves

34 - 40

17.2 - 20.7

6.0

7.5

9

Strong gale

High waves

41 - 47

20.8 - 24.4

7.0

10.0

10

Storm

Very high waves

48 - 55

24.5 - 28.4

9.0

12.5

11

Violent storm

Exceptionally high waves

56 - 63

28.5 - 32.6

11.5

16.0

12

Hurricane

Exceptionally high waves

64 - 71

32.7 - 36.9

14.0

> 16

13

Hurricane

Exceptionally high waves

72 - 80

37.0 - 41.4

> 14

> 16

14

Hurricane

Exceptionally high waves

81 - 89

41.5 - 46.1

> 14

> 16

15

Hurricane

Exceptionally high waves

90 - 99

46.2 - 50.9

> 14

> 16

16

Hurricane

Exceptionally high waves

100 - 109

51.0 - 56.0

> 14

> 16

17

Hurricane

Exceptionally high waves

109 - 118

56.1 - 61.2

> 14

> 16