27
Beaufort Scale
Description
Wind Speed
Land Condition
0
Calm. Smoke rises vertically.
1
Smoke drift indicates wind direction.
Leaves and wind vanes are stationary.
2
Wind felt on exposed skin. Leaves rustle.
Wind vanes begin to move.
Light flags extended.
3
Leaves and small twigs constantly moving,
4
Dust and loose paper raised. Small
branches begin to move.
5
Branches of a moderate size move.
Small trees in leaf begin to sway.
6
Large branches in motion. Whistling heard
in overhead wires. Umbrella use becomes
difficult. Empty plastic bins tip over.
7
Whole trees in motion. Effort needed to
walk against the wind.
8
Some twigs broken from trees.
Cars veer on road. Progress on foot is
seriously impeded
9
Some branches break off trees, and some
small trees blow over. Construction /
temporary signs and barricades blow over.
Severe widespread damage to vegetation
and structures. Debris and unsecured
objects are hurled about.
10
Trees are broken off or uprooted,
structural damage likely.
11
Widespread vegetation and structural
damage likely.
12
Calm
Light air
Light breeze
Gentle breeze
Moderate
breeze
Fresh breeze
Strong breeze
High wind
Gale
Strong gale
Storm
Violent storm
Hurricane force
< 1 km/h
< 1 mph
< 1 knots
< 0.3 m/s
1.1 ~ 5km/h
1 ~ 3 mph
1 ~ 3 knots
0.3 ~ 1.5 m/s
6 ~ 11 km/h
4 ~ 7 mph
4 ~ 6 knots
1.6 ~ 3.3 m/s
12 ~ 19 km/h
8 ~ 12 mph
7 ~ 10 knots
3.4 ~ 5.4 m/s
20 ~ 28 km/h
13 ~ 17 mph
11 ~ 16 knots
5.5 ~ 7.9 m/s
29 ~ 38 km/h
18 ~ 24 mph
17 ~ 21 knots
8.0 ~ 10.7 m/s
39 ~ 49 km/h
25 ~ 30 mph
22 ~ 27 knots
10.8 ~ 13.8 m/s
50 ~ 61 km/h
31 ~ 38 mph
28 ~ 33 knots
13.9 ~ 17.1 m/s
62 ~ 74 km/h
39 ~ 46 mph
34 ~ 40 knots
17.2 ~ 20.7 m/s
75 ~ 88 km/h
47 ~ 54 mph
41 ~ 47 knots
20.8 ~ 24.4 m/s
89 ~ 102 km/h
55 ~ 63 mph
48 ~ 55 knots
24.5 ~ 28.4 m/s
103 ~ 117 km/h
64 ~ 73 mph
56 ~ 63 knots
28.5 ~ 32.6 m/s
≥ 118 km/h
≥ 74 mph
≥ 64 knots
≥ 32.7 m/s
