Sea State

Beaufort No.

Description

Velocity in Knots

Velocity in m/s.

Sea State

Term

Code

Ht of waves in metres

Like a mirror

0

Calm

<1

0-0.2

Calm glassy

0

0

Ripples

1

Light airs

1-3

0.3-1.5

Calm rippled

1

0-0.1

Small wavelets

2

Light breeze

4-6

1.6-3.3

Smooth wavelets

2

0.1-0.5

Large wavelets

3

Gentle breeze

7-10

3.4-5.4

Slight

3

0.5-1.25

Small waves, breaking

4

Mod. breeze

11-16

5.5-7.9

Moderate

4

1.25-2.5

Moderate waves, foam

5

Fresh breeze

17-21

8.0-10.7

Rough

5

2.5-4

Large waves, foam and spray

6

Strong breeze

22-27

10.8-13.8

 Very rough

Sea heads up, foam in streaks

7

Near gale

28-33

13.9-17.1

6

4-6

Higher long waves, foam in streaks

8

Gale

34-40

17.2-20.7

High waves, dense foam, spray impairs visibility

9

Strong gale

41-47

20.8-24.4

High

7

6-9

Very high tumbling waves, surface white with foam, vis. affected

10

Storm

48-55

24.5-28.4

Very high

8

9-14

Exceptionally high waves, sea covered in foam, visibility affected

11

Violent storm

56-63

28.5-32.6

Phenomenal

9

Over 14

Air filled with spray and foam, visibility severely impaired

12

Hurricane

>64

>32.7