Beaufort Wind Scale

Beaufort
Force

Windspeed
Knots

Description

Sea Condition

0

0

 Calm Sea like a mirror

1

1 - 3

 Light Air Ripples but without foam crests

2

4 - 6

 Light Breeze Small wavelets. Crests do not break

3

7 - 10

 Gentle Breeze Large wavelets. Perhaps scattered white horses

4

11 - 16

 Moderate Breeze Small waves. Fairly frequent white horses.

5

17 - 21

 Fresh Breeze Moderate waves, many white horses

6

22 - 27

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

7

28 - 33

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

8

34 - 40

 Gale Moderately high waves, crests begin to break into spindrift

9

41 - 47

 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

 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

 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+

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