Kilometres per hour (max)
| Description | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | |
Description | Calm | Light air | Light breeze | Gentle breeze | Moderate breeze | Fresh breeze | Strong breeze | High wind | Gale | Strong gale | Storm | Violent storm | Hurricane force |
Sea conditions | Flat. | Ripples without crests. | Small wavelets. Crests of glassy appearance, not breaking | Large wavelets. Crests begin to break; scattered whitecaps | Small waves with breaking crests. Fairly frequent white horses. | Moderate waves of some length. Many white horses. Small amounts of spray. | Long waves begin to form. White foam crests are very frequent. Some airborne spray is present. | Sea heaps up. Some foam from breaking waves is blown into streaks along wind direction. Moderate amounts of airborne spray. | Moderately high waves with breaking crests forming spindrift. Well-marked streaks of foam are blown along wind direction. Considerable airborne spray. | High waves whose crests sometimes roll over. Dense foam is blown along wind direction. Large amounts of airborne spray may begin to reduce visibility. | 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. | 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. | Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility. |
Land conditions | Calm. Smoke rises vertically. | Smoke drift indicates wind direction, still wind vanes. | Wind felt on exposed skin. Leaves rustle, vanes begin to move. | Leaves and small twigs constantly moving, light flags extended. | Dust and loose paper raised. Small branches begin to move. | Branches of a moderate size move. Small trees in leaf begin to sway. | Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic garbage cans tip over. | Whole trees in motion. Effort needed to walk against the wind. | Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impeded. | Some branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over. | Trees are broken off or uprooted, saplings bent and deformed. Poorly attached asphalt shingles and shingles in poor condition peel off roofs. | 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. | Very widespread damage to vegetation. Some windows may break; mobile homes and poorly constructed sheds and barns are damaged. Debris may be hurled about. |
| Wind speed | |||||||||||||
| 0 | 1.1 | 5.6 | 12 | 20 | 29 | 39 | 50 | 62 | 75 | 89 | 103 | 118 | |
| 1 | 5.5 | 11 | 19 | 28 | 38 | 49 | 61 | 74 | 88 | 102 | 117 | 200 | |
| 0 | 1 | 4 | 8 | 13 | 18 | 25 | 31 | 39 | 47 | 55 | 64 | 73 | |
| 1 | 3 | 7 | 12 | 17 | 24 | 30 | 38 | 46 | 54 | 63 | 72 | 100 | |
| 0 | 1 | 3 | 7 | 11 | 16 | 21 | 27 | 34 | 41 | 48 | 56 | 64 | |
| 1 | 2 | 6 | 10 | 15 | 20 | 26 | 33 | 40 | 47 | 55 | 63 | 100 | |
| 0 | 0.3 | 1.6 | 3.4 | 5.5 | 8.0 | 10.8 | 13.9 | 17.2 | 20.8 | 24.5 | 28.5 | 32.7 | |
| 0.3 | 1.5 | 3.4 | 5.4 | 7.9 | 10.7 | 13.8 | 17.1 | 20.7 | 24.4 | 28.4 | 32.6 | 50 | |
| Wave height | |||||||||||||
| 0 | 0.01 | 0.2 | 0.5 | 1 | 2 | 3 | 4 | 5.5 | 7 | 9 | 11.5 | 14 | |
| 0 | 0.2 | 0.5 | 1 | 2 | 3 | 4 | 5.5 | 7.5 | 10 | 12.5 | 16 | 20 | |
| 0 | 0.01 | 1 | 2 | 3.5 | 6 | 9 | 13 | 18 | 23 | 29 | 37 | 46 | |
| 0 | 1 | 2 | 3.5 | 6 | 9 | 13 | 19 | 25 | 32 | 41 | 52 | 100 |