| Beaufort number |
Description |
Wind speed (mph) |
Wave height (ft) |
Sea conditions |
Land conditions |
| 0 |
Calm |
< 1 |
0 |
Flat. |
Calm. Smoke rises vertically. |
| 1 |
Light air |
1-3 |
0-1 |
Ripples without crests. |
Smoke drift indicates wind direction and wind vanes cease moving. |
| 2 |
Light breeze |
4-7 |
1-2 |
Small wavelets. Crests of glassy appearance, not breaking |
Wind felt on exposed skin. Leaves rustle and wind vanes begin to move. |
| 3 |
Gentle breeze |
8-12 |
2-3.5 |
Large wavelets. Crests begin to break; scattered whitecaps |
Leaves and small twigs constantly moving, light flags extended. |
| 4 |
Moderate breeze |
13-17 |
3.5-6 |
Small waves with breaking crests. Fairly frequent whitecaps. |
Dust and loose paper raised. Small branches begin to move. |
| 5 |
Fresh breeze |
18-24 |
6-9 |
Moderate waves of some length. Many whitecaps. Small amounts of spray. |
Branches of a moderate size move. Small trees in leaf begin to sway. |
| 6 |
Strong breeze |
25-30 |
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, Moderate gale, Near gale |
31-38 |
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. |
| 8 |
Gale, Fresh gale |
39-46 |
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 |
47-54 |
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. |
| 10 |
Storm, Whole gale |
55-63 |
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 |
47-52 |
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 Force |
> 73 |
> 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. |
