| Strength | Values | Effect on Land | Effect on Ocean |
|---|---|---|---|
| Still | 0-19 km/h | Wind felt on face; leaves rustle; | Sea like a mirror with small wavelets forming but not breaking, a glassy appearance is maintained. |
| Light | 20-29 km/h | Raises dust and loose paper; small branches are moved. | Small waves - becoming longer; fairly frequent white horses. |
| Medium | 30-39 km/h | Small trees in leaf begin to sway; crested wavelets form on inland waters | Moderate waves, taking a more pronounced long form; many white horses are formed - a chance of some spray |
| Strong | 40-49 km/h | Large branches in motion; whistling heard in telephone wires; umbrellas used with difficulty. | Large waves begin to form; the white foam crests are more extensive with probably some spray |
| X-Strong | 50 km/h + | Whole trees in motion; inconvenience felt when walking against wind. | Sea heaps up and white foam from breaking waves begins to be blown in streaks along direction of wind. |