Beaufort Force |
Description |
Sea State |
Speed (mph) |
0 |
Calm |
Sea like a mirror |
<
1 |
1 |
Very Light |
Ripples with appearance of scales, no foam crests |
1 - 3 |
2 |
Light breeze |
Wavelets, small but pronounced. Crests with glassy appearance, but do not break. |
4 -7 |
3 |
Gentle breeze |
Large wavelets, crests begin to break. Glassy looking foam, occasional white horses. |
8 - 12 |
4 |
Moderate breeze |
Small waves becoming longer, frequent white horses. |
13 - 18 |
5 |
Fresh breeze |
Moderate waves of pronounced long form. Many white horses, some spray. |
19 - 24 |
6 |
Strong breeze |
Some large waves, extensive white foam crests, some spray. |
25 - 31 |
7 |
Near gale |
Sea heaped up, white foam from breaking waves blowing in streaks with the wind. |
32 - 38 |
8 |
Gale |
Moderately high and long waves. Crests break into spin drift, blowing foam in well marked streaks. |
39 - 46 |
9 |
Strong gale |
High waves, dense foam streaks in wind, wave crests topple, tumble and roll over. Spray reduces visability. |
47 - 54 |
10 |
Storm |
Very high waves with long overhanging crests. Dense blowing foam, sea surface appears white. Heavy tumbling of sea, shock-like, poor visability. |
55 - 63 |
11 |
Violent storm |
Exceptionally high waves, sometimes concealing small and medium sized ships. Sea completely covered with long white patches of foam. Edges of wave crests blown into froth . Poor visibility. |
64 - 73 |
12 |
Hurricane |
Air filled with foam and spray, sea white with driving spray, poor visibility. |
>74 |