The Extended Beaufort Wind Scale

The Beaufort wind scale was devised in 1805 by British Rear-Admiral, Sir Francis Beaufort (1774–1857) and was extended in 1946.

Beaufort scale
Wind speed at 10 m
Wave height (m)
WMO classification
Appearance of wind effects
Tropical Cyclone Category
m/s
Knots
km/h
On the sea
On land
0
0.0–0.2
< 1
< 1
Calm
Sea surface smooth and mirror-like
Calm, smoke rises vertically
1
0.3–1.5
1–3
1–5
0.1
Light air
Scaly ripples, no foam crests
Smoke drift indicates wind direction, still wind vanes
2
1.6–3.3
4–6
6–11
0.2
Light breeze
Small wavelets, crests glassy, no breaking
Wind felt on face, leaves rustle, vanes begin to move
3
3.4–5.4
7–10
12–19
0.6
Gentle breeze
Large wavelets, crests begin to break, scattered whitecaps
Leaves and small twigs constantly moving, light flags extended
4
5.5–7.9
11–16
20–28
1
Moderate breeze
Small waves 1–4 ft. becoming longer, numerous whitecaps
Dust, leaves, and loose paper lifted, small tree branches move
5
8.0–10.7
17–21
29–38
2
Fresh breeze
Moderate waves 4–8 ft taking longer form, many whitecaps, some spray
Small trees in leaf begin to sway
6
10.8–13.8
22–27
39–49
3
Strong breeze
Larger waves 8–13 ft, whitecaps common, more spray
Larger tree branches moving, whistling in wires
Tropical Depression
7
13.9–17.1
28–33
50–61
4
Near gale
Sea heaps up, waves 13–19 ft, white foam streaks off breakers
Whole trees moving, resistance felt walking against wind
8
17.2–20.7
34–40
62–74
5.5
Gale
Moderately high (18–25 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks
Twigs breaking off trees, generally impedes progress
Tropical Storm
9
20.8–24.4
41–47
75–88
7
Strong gale
High waves (23–32 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility
Slight structural damage occurs, slate blows off roofs
10
24.5–28.4
48–55
89–102
9
Storm
Very high waves (29–41 ft) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility
Seldom experienced on land, trees broken or uprooted, ‘considerable structural damage’
Severe Tropical Storm
11
28.5–32.6
56–63
103–117
11.5
Violent storm
Exceptionally high (37–52 ft) waves, foam patches cover sea, visibility more reduced
12
32.7–36.9
64–71
118–133
14
Hurricane
Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced
Typhoon
13
37.0–41.4
72–80
134–149
14
41.5–46.1
81–89
150–166
Severe Typhoon
15
46.2–50.9
90–99
167–183
16
51.0–56.0
100–108
184–201
Super Typhoon
17
56.1–61.2
109–118
202–220
61.3–
119–
221–