THE BEAUFORT SCALE

FORCE STRENGTH WIND SPEED KM/H * WIND SPEED MPH * EFFECT
0 CALM 0-1 - Smoke rises vertically.
1 LIGHT AIR 1-5 1-3 Smoke drifts.
2 SLIGHT BREEZE 6-11 4-7 Leaves rustle, weather vanes move, wind felt on face.
3 GENTLE BREEZE 12-19 8-12 Light flags unfurl, leaves and twigs on trees move steadily.
4 MODERATE BREEZE 20-28 13-18 Small branches move, loose dust and paper fly about.
5 FRESH BREEZE 29-38 19-24 Leafy shrubs and trees sway.
6 STRONG BREEZE 39-49 25-31 Big branches move, wind pulls umbrellas.
7 HIGH WIND 50-61 32-38 Trees sway, walkers push into the wind.
8 GALE 62-74 39-46 Twigs break off trees, walking is hard.
9 STRONG GALE 75-88 47-54 Shingles, slates, and branches are blown off. Slight building damage.
10 STORM 89-102 55-63 Serious building damage, trees uprooted.
11 VIOLENT STORM 103-117 64-72 Widespread damage, wild storm.
12 HURRICANE ABOVE 117 ABOVE 73 Violent destruction of buildings & vehicles.
* KM/H = Kilometers per hour
  MPH = Miles per hour