| Code | Speed
mph | Speed
kph | Description | Effects |
|---|
|
0 |
below 1 |
below 1 |
Calm |
Smoke rises vertically |
| 1 |
2-3 |
1-5 |
Light Air |
Smoke drifts slowly |
| 2 |
4-7 |
6-11 |
Light Breeze |
Leaves rustle,
vanes begin to move |
| 3 |
8-12 |
12-19 |
Gentle Breeze |
Leaves and twigs move |
|
4 |
13-18 |
20-29 |
Moderate breeze |
Small branches move,
Dust blown about |
| 5 |
19-24 |
30-38 |
Fresh breeze |
Small trees sway |
| 6 |
25-31 |
39-51 |
Strong Breeze |
Large Branches sway,
Utility wires whistle |
| 7 |
32-38 |
51-61 |
Near gale |
Trees sway, difficult
to against wind |
| 8 |
39-40 |
62-74 |
Gale |
Twigs snap off trees |
| 9 |
47-54 |
75-86 |
Strong Gale |
Branches break,
Minor structural damage |
| 10 |
55-63 |
87-101 |
Whole Gale |
Trees Uprooted, Significant
structural damage |
| 11 |
64-74 |
102-120 |
Storm |
Widespread damage |
| 12 |
Above 74 |
Above 120 |
Hurricane |
Widespread destruction |