Table 4 Smithsonian and USSG Wind Scale conversions.
USSG scale | USSG description | Smithsonian scale | Smithsonian description | Smithsonian range Miles/ hour | Eqv Beaufort | Eqv knots | Eqv m/s |
|---|---|---|---|---|---|---|---|
0 | calm | ||||||
1 | Very gentle breeze | 1 | Very light breeze | 2 | 1 | 1.7 | 1 |
2 | Gentle breeze | 2 | Gentle breeze | 4 | 2 | 3.5 | 2 |
3 | Fresh breeze | 3 | Fresh breeze | 12 | 3 | 10 | 5 |
4 | Strong wind | 4 | Strong breeze | 25 | 5 | 21 | 10 |
5 | Very strong wind | 5 | High wind | 35 | 7 | 30 | 15 |
6 | Violent storm | 6 | Gale | 45 | 8 | 40 | 20 |
7 | Strong gale | 60 | 9 | 52 | 25 | ||
8 | Violent gale | 75 | 11 | 65 | 35 | ||
9 | Hurricane | 90 | 12 | 78 | 40 | ||
10 | Most violent hurricane | 100 | — | 87 | 45 |
