| No. | MPH | KmPH | Status | Sea | Land |
| 0 | < 1 | < 1.6 | CALM | Flat calm, like a mill pond. Calm. | Smoke will rise vertically. |
| 1 | 1 - 3 | 1.6 - 4.8 | LIGHT AIR | Ripples with the appearance of scales; no foam crests. Calm. | Rising smoke drifts, weather vane is inactive |
| 2 | 4 - 7 | 6.4 - 11.3 | LIGHT BREEZE | Small wavelets; crests of glassy apprearance, not breaking. Calm. | Leaves rustle, can feel wind on your face, weather vane begins to move. |
| 3 | 8 - 12 | 12 - 19 | GENTLE BREEZE | Large wavelets; crests begin to break; scattered whitecaps. Smooth. | Leaves and twigs move around. Light weight flags extend. |
| 4 | 13 - 18 | 20 - 30 | MODERATE BREEZE | Small waves, becoming longer; numerous whitecaps. Slight. | Moves thin branches, raises dust and paper. |
| 5 | 19 - 24 | 30 - 39 | FRESH BREEZE | Moderate waves, taking longer form; many whitecaps; some spray. Moderate. | Trees sway. |
| 6 | 25 - 31 | 40 - 50 | STRONG
BREEZE
NEAR GALE |
Larger waves forming; whitecaps everywhere; more spray. Rough. | Large tree branches move, open wires (such as telegraph wires) begin to "whistle", umbrellas are difficult to keep under control. |
| 7 | 32 - 38 | 51 - 61 | MODERATE GALE | Sea heaps up; white foam from breaking waves begins to blow in streaks. Very Rough. | Large trees begin to sway, noticeably difficult to walk. |
| 8 | 39 - 46 | 62 - 74 | FRESH GALE | Moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown into wellmarked streaks. Very Rough. | Twigs and small branches are broken from trees, walking into the wind is very difficult. |
| 9 | 47 - 54 | 75 - 87 | STRONG GALE | High waves; seas begins to roll; dense streaks of foam; spray may reduce visibility. Very Rough. | Slight damage occurs to buildings, shingles are blown off of roofs. |
| 10 | 55 - 63 | 88 - 101 | STORM | Very
high waves with overhanging crests; sea takes white appearance as foam
is blown in very dense streaks; rolling is heavy and visibility is reduced.
High. |
Large trees are uprooted, building damage is considerable |
| 11 | 64 - 72 | 102 - 116 | VIOLENT STORM | Exceptionally high waves; sea covered with white foam patches; visibility still more reduced. | Extensive widespread damage. These typically occur only at sea, and rarely inland. |
| 12 | 73 > | 116 > | HURRICANE | Air filled with foam; sea completely white with driving spray; visibility still more reduced. | Extreme destruction. |
The term "squall" is used to refer to a sudden wind-speed increase, both historically and in the present day. In 1962 the World Meteorological Organization (WMO) defined that to be classified as a squall, the wind must increase at least 8 m/s (17.9 mph) and must attain a top speed of at least 11 m/s (24.6 mph), lasting at least one minute in duration
Wind
Direction (degrees azimuth)
The value
0° means North.
The value
90° means East.
The value 180° means
South.
The value 270° means
West.
