| 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. |
