Beaufort

  knots  

            km/h          

          m/sec         

1

  1 -  3 kn

    1.9 -     6.4 km/h

  0.5 -   1.8 m/sec

light air

2

  4 -  6 kn

    6.5 -   12.0 km/h

  1.9 -   3.3 m/sec

light breeze

3

  7 - 10 kn

  12.1 -   19.4 km/h

  3.4 -   5.4 m/sec

gentle breeze

4

11 - 15 kn

  19.5 -   28.7 km/h

  5.5 -   7.9 m/sec

moderate breeze

5

16 - 21 kn

  28.8 -   39.8 km/h

  8.0 - 11.0 m/sec

fresh wind

6

22 - 27 kn

  39.9 -   50.9 km/h

11.1 - 14.1 m/sec

strong wind

7

28 - 33 kn

  51.0 -   62.0 km/h

14.2 - 17.2 m/sec

moderate gale

8

34 - 40 kn

  62.1 -   75.0 km/h

17.3 - 20.8 m/sec

fresh gale

9

41 - 47 kn

  75.1 -   87.9 km/h

20.9 - 24.4 m/sec

strong gale

10

48 - 55 kn

  88.0 - 102.8 km/h

24.5 - 28.5 m/sec

full gale

11

56 - 63 kn

102.9 - 117.6 km/h

28.6 - 32.6 m/sec

storm

12

> 63 kn

> 117.6 km/h

> 32.6 m/sec

hurricane