| Beaufort Number or Force |
Wind Speed and Description |
Effects Land/Sea |
Probable Wave Height |
| MPH |
Knots |
Description |
| 0 |
<1 |
<1 |
Calm |
Still, calm air, smoke will rise vertically. Smooth like a mirror. |
0 |
| 1 |
1-3 |
1-3 |
Light Air |
Rising smoke drifts, wind vane is inactive. Small ripples like fish scales. |
¼ - ½ foot |
| 2 |
4-7 |
4-6 |
Light Breeze |
Leaves rustle, can feel wind on your face, wind vanes begin to move. Short, small pronounced wavelets with no crests. |
¼ - ½ foot |
| 3 |
8-12 |
7-10 |
Gentle Breeze |
Leaves and small twigs move, light weight flags extend. Large wavelets, crests start to break, some whitecaps. |
2 feet |
| 4 |
13-18 |
11-16 |
Moderate Breeze |
Small branches move, raises dust, leaves and paper. Small waves develop, becoming longer, whitecaps. |
4 feet |
| 5 |
19-24 |
17-21 |
Fresh Breeze |
Small trees sway. Moderate lengthening waves, with many white caps and some spray. |
6 feet |
| 6 |
25-31 |
22-27 |
Strong Breeze |
Large tree branches move, telephone wires begin to "whistle"Large waves, extensive white caps, some spray. |
10 feet |
| 7 |
32-38 |
28-33 |
Near Gale |
Large trees sway, becoming difficult to walk. Heaps of waves, with some breakers whose foam is blown downwind in streaks. |
14 feet |
| 8 |
39-46 |
34-40 |
Gale |
Twigs and small branches are broken from trees, walking is difficult. Moderately large waves with blown foam. |
18 feet |
| 9 |
47-54 |
41-47 |
Strong Gale |
Slight damage occurs to buildings, shingles are blown off of roofs. Rolling seas, dense foam, Blowing spray reduces visibility. |
23 feet |
| 10 |
55-63 |
48-55 |
Whole Gale or Storm |
Trees are broken or uprooted, building damage is considerable. Very high waves with long, overhanging crests. The sea looks white, visibility is greatly reduced. |
29 feet |
| 11 |
64-72 |
56-63 |
Violent Storm |
Extensive widespread damage. Wave edges are blown into froth, and the sea is covered with patches of foam. |
37 feet |
| 12 |
73+ |
64+ |
Hurricane |
Extreme destruction, devastation. The air is filled with foam and spray, and the sea is completely white, little visibility. |
45 feet |
