The wind speeds shown below are those measured by an anemometer at a height of ten metres above the ground. At two metres above the ground the wind speed maybe 50 – 70% less than those shown in this table.
| Wind Force | Description | km/h | Effect |
|---|---|---|---|
| 0 | Calm | <1 | Smoke rises vertically |
| 1 | Light Air | 1 - 5 | Direction shown by smoke drift but not by wind vanes |
| 2 | Light Breeze | 6 -11 | Wind felt on face; leaves rustle; wind vane moved by wind |
| 3 | Gentle Breeze | 12 - 19 | Leaves and small twigs in constant motion; light flags extended |
| 4 | Moderate Breeze | 20 - 28 | Raises dust and loose paper; small branches moved. |
| 5 | Fresh Breeze | 29 - 38 | Small trees in leaf begin to sway; crested wavelets form on inland waters. |
| 6 | Strong Breeze | 39 - 49 | Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty. |
| 7 | Near Gale | 50 - 61 | Whole trees in motion; inconvenience felt when walking against the wind. |
| 8 | Gale | 62 - 74 | Twigs break off trees; generally impedes progress. |
| 9 | Strong Gale | 75 - 88 | Slight structural damage (chimney pots and slates removed). |
| 10 | Storm | 89 - 102 | Seldom experienced inland; trees uprooted; considerable structural damage |
| 11 | Violent Storm | 103 - 117 | Very rarely experienced; accompanied by widespread damage. |
| 12 | Hurricane | 118 plus | Devastation |