| Force | Description | Result | Wind Speed | Wind Speed | ||||||
| mph | kph | |||||||||
| 0 | Calm | Smoke rises vertically | 0 | - | 1 | 0 | - | 1 | ||
| 1 | Light air | Wind direction indicated by smoke but not wind vanes | 1 | - | 3 | 1 | - | 5 | ||
| 2 | Light breeze | Wind noticeable, leaves move, wind vane moves. | 4 | - | 7 | 6 | - | 11 | ||
| 3 | Gentle breeze | Leaves and small twigs in constant motion. | 7 | - | 12 | 12 | - | 19 | ||
| 4 | Moderate breeze | Wind raises dust and loose paper. Small branches are moved. | 12 | - | 18 | 20 | - | 29 | ||
| 5 | Fresh breeze | Small trees in leaf start to sway.Crested wavelets form on inland waters. | 19 | - | 24 | 30 | - | 39 | ||
| 6 | Strong breeze | Large branches in motion, wind whistles. Umbrellas used with difficulty. | 25 | - | 31 | 40 | - | 50 | ||
| 7 | Near gale. | Trees in motion, awkward to walk against wind. | 32 | - | 38 | 51 | - | 61 | ||
| 8 | Gale | Twigs break, hard to walk. | 39 | - | 46 | 62 | - | 74 | ||
| 9 | Strong gale | Some structural damage may occur, slates removed etc. | 47 | - | 54 | 75 | - | 87 | ||
| 10 | Storm | Trees uprooted, considerable structural damage. | 55 | - | 63 | 88 | - | 101 | ||
| 11 | Violent storm | Widespread damage. | 63 | - | 73 | 102 | - | 117 | ||
| 12 | Hurricane | Widespread damage. | 73 | + | 118 | + | ||||