Beaufort scale

The Beaufort scale was developed in 1806 by the English Admiral Sir Francis Beaufort (1774 - 1857). It can be used to estimate wind strength based on the effects of the wind. It ranges from force 0 (calm) to force 12 (hurricane).

Beaufort degree Designation Average wind speed at 10m above open terrain Examples of the effects of wind inland
m/s km/h
0 calm
0 - 0.2 < 1
Smoke rises vertically
1 quiet draft
0.3 - 1.5 1 - 5
Wind direction evident from the draft of smoke
2 light breeze
1.6 - 3.3 6 - 11
Wind felt in the face, leaves and flags moving
3 light wind
3.4 - 5.4 12 - 19
Wind moves thin branches and stretches flags
4 moderate wind
5.5 - 7.9 20 - 28
Wind moves twigs and thinner branches, lifts dust and loose paper
5 fresh wind
8.0 - 10.7 29 - 38
small deciduous trees begin to sway, whitecaps form on the sea
6 strong wind
10.8 - 13.8 39 - 49
strong branches sway, umbrellas are difficult to hold
7 strong wind
13.9 - 17.1 50 - 61
noticeable inhibitions when walking against the wind, whole trees move
8 stormy wind
17.2 - 20.7 62 - 74
Branches break from trees, making it difficult to walk outdoors
9 Storm
20.8 - 24.4 75 - 88
Branches break off trees, minor damage to houses (roof tiles or chimneys lifted off)
10 severe storm
24.5 - 28.4 89 - 102
Wind breaks trees, major damage to houses
11 hurricane-force storm
28.5 - 32.6 103 - 117
Wind uproots trees, spreads storm damage
12 hurricane
from 32.7 from 118
severe devastation