Wind Speed in knots at ground level

Wave Height in feet

Description

Sea Condition

0

0 to 1

0

Calm

Flat

1

1 to 3

¼

Light Air

Ripples without Crests

2

4 to 8

½

Light Breeze

Small Wavelets

3

7 to 10

2.0

Gentle Breeze

Large Wavelets Scattered Whitecaps

4

11 to 16

3.5

Moderate Breeze

Small Waves Frequent Whitecaps

5

17 to 21

6.0

Fresh Breeze

Moderate waves (1.2M) Some Foam & Spray

6

22 to 27

9.5

Strong Breeze

Large Waves with Foam Crests & Spray

7

28 to 33

13.5

Moderate Gale

Sea Heaps Up & Foam begins to Streak

8

34 to 40

18.0

Fresh Gale

Moderately High Waves with Breaking Crests Forming Spindrift. Streaks of Foam

9

41 to 47

23.0

Strong Gale

High Waves (2.75M) with dense foam. Wave Crest start to Roll Over. Considerable Spray

10

48 to 55

29.0

Whole Gale/Storm

Very high Waves. The Sea Surface is White & Considerable Tumbling

11

56 to 53

37.0

Violent Storm

Exceptionally High Waves

12

64 plus

45.0

Hurricane

Hugh Waves. Air Filled with Foam & Spray. Sea completely white with driving spray