Beaufort
Wind Scale |
Force |
Wind Speed |
Description |
Effects on Land and at Sea |
mph |
km/hr |
knots |
0 |
<1 |
<1 |
<1 |
Calm |
Still, calm air, smoke will rise vertically. Water is mirror-like. |
1 |
1-3 mph |
1-5 kph |
1-3 knots |
Light Air |
Rising smoke drifts, wind vane is inactive. Small ripples appear on water surface. |
2 |
4-7 mph |
6-11 kph |
4-6 knots |
Light Breeze |
Leaves rustle,
can feel wind on your face, wind vanes begin to move. Small wavelets
develop, crests are glassy. |
3 |
8-12 mph |
12-19 kph |
7-10 knots |
Gentle Breeze |
Leaves and small twigs move, light weight flags extend. Large wavelets,
crests start to break, some whitecaps. |
4 |
13-18 mph |
20-28 kph |
11-16 knots |
Moderate Breeze |
Small branches
move, raises dust, leaves and paper. Small waves develop, becoming longer,
whitecaps. |
5 |
19-24
mph |
29-38
kph |
17-21
knots |
Fresh Breeze |
Small trees sway. White crested wavelets (whitecaps) form, some spray. |
6 |
25-31
mph |
39-49
kph |
22-27
knots |
Strong Breeze |
Large tree
branches move, telephone wires begin to "whistle", umbrellas are difficult
to keep under control. Larger waves form, whitecaps prevalent, spray. |
7 |
32-38
mph |
50-61
kph |
28-33
knots |
Moderate or
Near Gale |
Large trees sway, becoming difficult to walk. Larger waves develop, white
foam from breaking waves begins to be blown. |
8 |
39-46
mph |
62-74
kph |
34-40
knots |
Gale or Fresh Gale |
Twigs and small
branches are broken from trees, walking is difficult. Moderately large waves
with blown foam. |
9 |
47-54
mph |
75-88
kph |
41-47
knots |
Strong Gale |
Slight damage occurs to buildings, shingles are blown off of roofs. High
waves (6 meters), rolling seas, dense foam, Blowing spray reduces
visibility. |
10 |
55-63
mph |
89-102
kph |
48-55
knots |
Whole Gale or Storm |
Trees are broken
or uprooted, building damage is considerable. Large waves (6-9 meters),
overhanging crests, sea becomes white with foam, heavy rolling, reduced
visibility. |
11 |
64-72
mph |
103-117
kph |
56-63
knots |
Violent Storm |
Extensive widespread damage. Large waves (9-14 meters), white foam,
visibility further reduced. |
12 |
73+ mph |
118+ kph |
64+ knots |
Hurricane |
Extreme
destruction, devastation. Large waves over 14 meters, air filled with foam,
sea white with foam and driving spray, little visibility. |