Beaufort Scale

Beaufort
Force

Windspeed
Knots

Avg Wave Height

Description

Sea Condition

0

0

0 feet

Calm Sea like a mirror

1

1 - 3

< 1/2

Light Air Ripples but without foam crests

2

4 - 6

1/2 ft
(max 1)

Light Breeze Small wavelets. Crests do not break

3

7 - 10

2 ft
(max 3)

Gentle Breeze Large wavelets. Perhaps scattered white horses

4

11 - 16

3 ft
(max 5)

Moderate Breeze Small waves. Fairly frequent white horses.

5

17 - 21

6 ft
(max 8)

Fresh Breeze Moderate waves, many white horses

6

22 - 27

9 ft
(max 12)

Strong Breeze Large waves begin to form; white foam crests, probably spray

7

28 - 33

13 ft
(max 19)

Near Gale Sea heaps up and white foam blown in streaks along the direction of the wind

8

34 - 40

18 ft
(max 25)

Gale Moderately high waves, crests begin to break into spindrift

9

41 - 47

23 ft
(max 32)

Strong Gale High waves. Dense foam along the direction of the wind. Crests of waves begin to roll over. Spray may affect visibility

10

48 - 55

29 ft
(max 41)

Storm Very high waves with long overhanging crests. The surface of the sea takes a white appearance. The tumbling of the sea becomes heavy and shock like. Visibility affected

11

56 - 63

37 ft
(max 52)

Violent Storm Exceptionally high waves. The sea is completely covered with long white patches of foam lying in the direction of the wind. Visibility affected

12

64+

45+ ft

Hurricane The air is filled with foam and spray. Sea completely white with driving spray. Visibility very seriously affected.

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