|
Beaufort Number
|
Description
|
Wind Speed
|
Wave Height
|
Sea Conditions
|
Land Conditions
|
|
mph
|
km/h
|
kts
|
m
|
ft
|
|
0
|
Calm
|
< 1
|
< 1
|
< 1
|
0
|
0
|
Flat
|
Calm. Smoke rises vertically
|
|
1
|
Light air
|
1 - 3
|
1.1 - 5.5
|
1 - 2
|
0 - 0.2
|
0 - 1
|
Ripples without crests
|
Wind motion visible in smoke
|
|
2
|
Light breeze
|
4 - 7
|
5.6 - 11
|
3 - 6
|
0.2 - 0.5
|
1 - 2
|
Small wavelets. Crests of glassy appearance, not breaking
|
Wind felt on exposed skin. Leaves rustle
|
|
3
|
Gentle breeze
|
8 - 12
|
12 - 19
|
7 - 10
|
0.5 - 1
|
2 - 3.5
|
Large wavelets. Crests begin to break; scattered whitecaps
|
Leaves and smaller twigs in constant motion
|
|
4
|
Moderate breeze
|
13 - 17
|
20 - 28
|
11 - 15
|
1 - 2
|
3.5 - 6
|
Small waves with breaking crests. Fairly frequent white horses
|
Dust and loose paper raised. Small branches begin to move
|
|
5
|
Fresh breeze
|
18 - 24
|
29 - 38
|
16 - 20
|
2 - 3
|
6 - 9
|
Moderate waves of some length. Many white horses. Small amounts of spray
|
Branches of a moderate size move. Small trees begin to sway
|
|
6
|
Strong breeze
|
25 - 30
|
39 - 49
|
21 - 26
|
3 - 4
|
9 - 13
|
Long waves begin to form. White foam crests are very frequent. Some airborne spray is present
|
Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic rubbish bins tip over
|
|
7
|
High wind, moderate gale, near gale
|
31 - 38
|
50 - 61
|
27 - 33
|
4 - 5.5
|
13 - 19
|
Sea heaps up. Some foam from breaking waves is blown into streaks along wind direction. Moderate amounts of airborne spray
|
Whole trees in motion. Effort needed to walk against the wind. Swaying of skyscrapers may be felt, especially by people on upper floors.
|
|
8
|
Gale, fresh gale
|
39 - 46
|
62 - 74
|
34 - 40
|
5.5 - 7.5
|
17.2 - 20.7
|
Moderately high waves with breaking crests forming spindrift. Well-marked streaks of foam are blown along wind direction. Considerable airborne spray
|
Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded
|
|
9
|
Strong gale
|
47 - 54
|
75 - 88
|
41 - 47
|
7 - 10
|
23 - 32
|
High waves whose crests sometimes roll over. Dense foam is blown along wind direction. Large amounts of airborne spray may begin to reduce visibility
|
Some branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. Damage to circus tents and canopies
|
|
10
|
Storm, whole gale
|
55 - 63
|
89 - 102
|
48 - 55
|
9 - 12.5
|
29 - 41
|
Very high waves with overhanging crests. Large patches of foam from wave crests give the sea a white appearance. Considerable tumbling of waves with heavy impact. Large amounts of airborne spray reduce visibility
|
Trees are broken off or uprooted, saplings bent and deformed. Poorly attached asphalt shingles and shingles in poor condition peel off roofs
|
|
11
|
Violent storm
|
64 - 72
|
103 - 117
|
56 - 63
|
11.5 - 16
|
37 - 52
|
Exceptionally high waves. Very large patches of foam, driven before the wind, cover much of the sea surface. Very large amounts of airborne spray severely reduce visibility
|
Widespread damage to vegetation. Many roofing surfaces are damaged; asphalt tiles that have curled up and/or fractured due to age may break away completely
|
|
12
|
Hurricane
|
≥ 73
|
≥ 118
|
≥ 64
|
≥17
|
≥53
|
Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility
|
Very widespread damage to vegetation. Some windows may break; mobile homes and poorly constructed sheds and barns are damaged. Debris may be hurled about
|
