| Windforce | Average windspeed | Sea | ||||||
| Beaufort | Name | m/s | km/h | knots | miles/h | Force | State | Waves* |
| 0 | Calm |
0-0,2 |
< 1 |
< 1 |
<1 | 0 | Calm (glassy) | - |
| 1 | Light air |
0,3-1,5 |
1-5 |
1-3 |
1-3 | 1 | Calm (rippled) | 0,1 |
| 2 | Light breeze |
1,6-3,3 |
6-11 |
4-6 |
4-7 | 2 | Smooth (wavelets) | 0,2 |
| 3 | Gentle breeze |
3,4-5,4 |
12-19 |
7-10 |
8-11 | 3 | Slight | 0,6 |
| 4 | Moderate breeze |
5,5-7,9 |
20-28 |
11-16 |
13-18 | 3-4 | Slight-Moderate | 1 |
| 5 | Fresh breeze |
8,0-10,7 |
29-38 |
17-21 |
19-24 | 4 | Moderate | 2 |
| 6 | Strong breeze |
10,8-13,8 |
39-49 |
22-27 |
25-31 | 5 | Rough | 3 |
| 7 | Near gale |
13,9-17,1 |
50-61 |
28-33 |
32-38 | 5-6 | Rough-Very rough | 4 |
| 8 | Gale |
17,2-20,7 |
62-74 |
34-40 |
39-46 | 6-7 | Very rough-High | 5.5 |
| 9 | Strong gale |
20,8-24,4 |
75-88 |
41-47 |
47-54 | 7 | High | 7 |
| 10 | Storm |
24,5-28,4 |
89-102 |
48-55 |
55-63 | 8 | Very High | 9 |
| 11 | Violent storm |
28,5-32,6 |
103-117 |
56-63 |
64-74 | 8 | Very High | 11,5 |
| 12 | Hurricane |
>= 32,7 |
>= 118 |
>= 64 |
>=75 | 9 | Phenomenal | 14+ |
One of the first scales to estimate wind speeds and the effects was created by Britain's Admiral Sir Francis Beaufort (1774-1857). He developed the scale in 1805 to help sailors estimate the winds via visual observations. The scale starts with 0 and goes to a force of 12. The Beaufort scale is still used today to estimate wind strengths.
