| Beaufort number |
Wind speed |
Description |
Wave height |
What the sea looks like |
What it looks like on land |
Sea state photo |
| km/h |
mph |
kts |
m/s |
m |
ft |
| 0 |
<1 |
<1 |
<1 |
<0.3 |
Calm |
0 |
0 |
Flat and little movement. |
Calm. Smoke rises vertically. |
 |
| 1 |
1-5 |
1-3 |
1-3 |
0.3-1.5 |
Light air |
0.1 |
0.33 |
Ripples without crests. |
Wind motion visible in smoke. |
 |
| 2 |
6-11 |
3-7 |
4-6 |
1.5-3.3 |
Light breeze |
0.2 |
0.66 |
Small wavelets. Crests of glassy appearance, not breaking |
Wind felt on exposed skin. Leaves rustle. |
 |
| 3 |
12-19 |
8-12 |
7-10 |
3.3-5.5 |
Gentle breeze |
0.6 |
2 |
Large wavelets. Crests begin to break; scattered whitecaps |
Leaves and smaller twigs in constant motion. |
 |
| 4 |
20-28 |
13-17 |
11-16 |
5.5-8.0 |
Moderate breeze |
1 |
3.3 |
Small waves. |
Dust and loose paper raised. Small branches begin to move. |
 |
| 5 |
29-38 |
18-24 |
17-21 |
8.0-10.8 |
Fresh breeze |
2 |
6.6 |
Moderate (1.2 m) longer waves. Some foam and spray. |
Branches of a moderate size move. Small trees begin to sway. |
 |
| 6 |
39-49 |
25-30 |
22-27 |
10.8-13.9 |
Strong breeze |
3 |
9.9 |
Large waves with foam crests and some spray. |
Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic garbage cans tip over. |
 |
| 7 |
50-61 |
31-38 |
28-33 |
13.9-17.2 |
High wind, Moderate Gale, Near Gale |
4 |
13.1 |
Sea heaps up and foam begins to streak. |
Whole trees in motion. Effort needed to walk against the wind. Swaying of skyscrapers may be felt, especially by people on upper floors. |
 |
| 8 |
62-74 |
39-46 |
34-40 |
17.2-20.7 |
Fresh Gale |
5.5 |
18 |
Moderately high waves with breaking crests forming spindrift. Streaks of foam. |
Twigs broken from trees. Cars veer on road. |
 |
| 9 |
75-88 |
47-54 |
41-47 |
20.7-24.5 |
Strong Gale |
7 |
23 |
High waves (6-7 m) with dense foam. Wave crests start to roll over. Considerable spray. |
Larger branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. Damage to circus tents and canopies. |
 |
| 10 |
89-102 |
55-63 |
48-55 |
24.5-28.4 |
Whole Gale/Storm |
9 |
29.5 |
Very high waves. 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 |
103-117 |
64-72 |
56-63 |
28.4-32.6 |
Violent storm |
11.5 |
37.7 |
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 vegetation damage. More damage to most roofing surfaces, asphalt tiles that have curled up and/or fractured due to age may break away completely. |
 |
| 12 |
≥118 |
≥73 |
≥64 |
≥32.6 |
Hurricane-force |
≥14 |
≥46 |
Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility. |
Considerable and widespread damage to vegetation, a few windows broken, structural damage to mobile homes and poorly constructed sheds and barns. Debris may be hurled about. |
 |
