Beaufort scale

Beaufort scale

Beaufort Wind Scale and Sea State Chart

Sea State

Beaufort Number

Terminology

Wind Speed (miles per hour)

Average Wave Height (feet)

Description

0

0

Calm

0-1

0

Sea like a mirror

1

1

Light air

1-3

0.005

Ripples with appearance of scales; no crests

2

2

Light breeze

4-7

0.18

Small wavelets; crests have glossy appearance but do not break.

3

3

Gentle breeze

8-12

0.19-1

Large wavelets, crests begin to break; foam of glossy appearance; a few white horses.

4

Moderate breeze

13-18

2-3

Small waves becoming longer form; many white horses formed; some spray

4

5

Fresh breeze

19-24

4-5

Moderate waves taking longer form; many white horses formed; some spray

6

Strong breeze

25-31

6-10

Large waves begin to form; many white crests more spray

7

Moderate gale

32-38

11-16

Sea heaps up; white foam from breaking waves begins to be blown in streaks

5

8

Fresh gale

39-46

17-28

Moderately high waves of greater length; edges of crests begin to break into spindrift; foam blown in well marked streaks spray affects visibility.

9

Strong gale (storm)

47-54

29-40

High waves; dense streaks of foam along wind direction; sea begins to roll; visibility affected

10

Whole gale (heavy storm)

55-63

41-59

Very high waves with long overhanging crests; sea takes white appearance; rolling heavy; visibility affected.

11

Violent storm

64-72

60-73

Exceptionally high waves; small and medium sized ships lost from view; crests blown into froth.

12

Hurricane

73-82

74-80

Air filled with foam and spray; sea completely white with driving spray; visibility very seriously affected.

Last modified: Tuesday, 6 December 2011, 6:41 AM