| Beaufort number |
Description |
Wind speed |
Wave height |
Sea conditions |
Land conditions |
Sea state photo |
| kts |
feet |
| 0 |
Calm |
< 1 |
0 |
Flat. |
Calm. Smoke rises vertically. |
 |
| 1 |
Light air |
1 - 2 |
0 - 1 |
Ripples without crests. |
Wind motion visible in smoke. |
 |
| 2 |
Light breeze |
3 - 6 |
1 - 2 |
Small wavelets. Crests of glassy appearance, not breaking |
Wind felt on exposed skin. Leaves rustle. |
 |
| 3 |
Gentle breeze |
7 - 10 |
2 - 3.5 |
Large wavelets. Crests begin to break; scattered whitecaps |
Leaves and smaller twigs in constant motion. |
 |
| 4 |
Moderate breeze |
11 - 15 |
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 |
16 - 20 |
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 |
21 - 26 |
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 garbage cans tip over. |
 |
| 7 |
High wind |
27 - 33 |
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 |
34 - 40 |
18 - 25 |
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 |
41 - 47 |
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 |
48 - 55 |
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 |
56 - 63 |
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 vegetation damage. Many roofing surfaces are damaged; asphalt tiles that have curled up and/or fractured due to age may break away completely. |
 |
| 12 |
Hurricane |
> 64 |
> 46 |
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. |
 |
