The Beaufort Scale

Number Name MPH Description
0 calm less than 1 calm; smoke rises vertically
1 light air 1-3 direction of wind shown by smoke but not by wind vanes
2 light breeze 4-7 wind felt on face; leaves rustle; ordinary vane moved by wind
3 gentle breeze 8-12 leaves and small twigs in constant motion; wind extends light flag
4 moderate breeze 13-18 raises dust and loose paper; small branches are moved
5 fresh breeze 19-24 small trees in leaf begin to sway; crested waves form on inland waters
6 strong breeze 25-31 large branches in motion; telegraph wires whistle; umbrellas used with difficulty
7 moderate gale (or near gale) 32-38 whole trees in motion; inconvenience in walking against wind
8 fresh gale 39-46 breaks twigs off trees; generally impedes progress
9 strong gale 47-54 slight structural damage; chimney pots and slates removed
10 whole gale (or storm) 55-63 trees uprooted; considerable structural damage occurs
11 storm (or violent storm) 64-72 very rarely experienced; accompanied by widespread damage
12 hurricane 73-136 devastation occurs