| 0 | Calm | < 1 | < 1 | < 1 | 0 | 0 | Flat | Calm. Smoke rises vertically |
| 1 | Light air | 1 - 3 | 1.1 - 5.5 | 1 - 2 | 0 - 0.2 | 0 - 1 | Ripples without crests | Wind motion visible in smoke |
| 2 | Light breeze | 4 - 7 | 5.6 - 11 | 3 - 6 | 0.2 - 0.5 | 1 - 2 | Small wavelets. Crests of glassy appearance, not breaking | Wind felt on exposed skin. Leaves rustle |
| 3 | Gentle breeze | 8 - 12 | 12 - 19 | 7 - 10 | 0.5 - 1 | 2 - 3.5 | Large wavelets. Crests begin to break; scattered whitecaps | Leaves and smaller twigs in constant motion |
| 4 | Moderate breeze | 13 - 17 | 20 - 28 | 11 - 15 | 1 - 2 | 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 | 18 - 24 | 29 - 38 | 16 - 20 | 2 - 3 | 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 | 25 - 30 | 39 - 49 | 21 - 26 | 3 - 4 | 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 rubbish bins tip over |
| 7 | High wind, moderate gale, near gale | 31 - 38 | 50 - 61 | 27 - 33 | 4 - 5.5 | 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 | 39 - 46 | 62 - 74 | 34 - 40 | 5.5 - 7.5 | 17.2 - 20.7 | 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 | 75 - 88 | 41 - 47 | 7 - 10 | 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 blow over |
| 10 | Storm, whole gale | 55 - 63 | 89 - 102 | 48 - 55 | 9 - 12.5 | 29 - 41 | Very high waves with overhanging crests. Large patches of foam, driven before the wind, cover much of the sea surface. Very 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 | 103 - 117 | 56 - 63 | 11.5 - 16 | 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 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 | ≥ 73 | ≥ 118 | ≥ 64 | ≥ 17 | ≥ 53 | 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 |