| Scale |
Wind |
Sea |
Waves (ft) |
km/h |
mph |
knot |
| 0 | Calm | Glassy | 0 | 1 | 1 | 1 |
| 1 | Light wind | Rippled | 1 | 5 | 3 | 3 |
| 2 | Light breeze | Smooth | 2 | 11 | 7 | 6 |
| 3 | Gentle breeze | Scattered Whitecaps | 3.5 | 19 | 12 | 10 |
| 4 | Moderate breeze | Frequent Whitecaps | 6 | 28 | 18 | 16 |
| 5 | Fresh breeze | Moderate Waves | 9 | 38 | 24 | 21 |
| 6 | Strong breeze | Rough | 13 | 49 | 31 | 27 |
Think carefully before going out on the sea when the wind is over 20 km/h.