How to Estimate Wind Speed
High winds can damage trees, homes and other buildings. Anemometers can provide exact measurements of wind speed, but you don't need them for everyday estimates. You can easily estimate wind speed by using your senses and observational skills. The Beaufort Wind Scale, although written in 1805, still helps you estimate wind speed by observing the environment. The Saffir-Simpson Hurricane Wind Scale modifies and expands Beaufort's scale for tropical storms and hurricanes.
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Instructions
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Look for smoke or steam rising, such as from chimneys or factories. Notice that wind vanes remain still. If the smoke is rising straight up in the air or drifting slightly, the calm or light wind measures from 0 to 3.5 miles per hour---0 to1 on the Beaufort scale or 0 to 3 knots.
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Check for the touch of wind on the face. Listen for leaves rustling on trees and small limbs moving. Observe that wind vanes begin to move. If you can barely feel the wind and leaves and vanes are moving softly, the light or gentle breeze measures between 4.5 and 11.5 miles per hour---2 to 3 on the Beaufort scale or 4 to 10 knots.
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See if the wind lifts dust, leaves or other light debris and moves small tree branches. Check if light flags remain extended. If so, the moderate breeze measures between 12.5 and 18.5 miles per hour---4 on the Beaufort scale or 11 to 16 knots.
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Watch for small trees swaying and larger branches moving. Listen for wires whistling. If noticeable, the fresh or strong breeze measures between 19.5 and 31 miles per hour---5 to 6 on the Beaufort scale or 17 to 27 knots.
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Observe if whole trees are moving or in motion. Feel for resistance when walking. If so, the near-gale or gale measures between 32 and 46 miles per hour---7 to 8 on the Beaufort scale or 28 to 40 knots.
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If the wind causes slight damage to buildings or trees, such as blowing shingles off roofs, the strong gale or storm measures from 47 to 63 miles per hour---9 to 10 on the Beaufort scale or 41 to 55 knots.
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Look for damage to buildings or snapped tree branches. These indicate winds between 74 and 95 mph---a Category 1 hurricane on the Saffir-Simpson Scale.
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More widespread damage to homes, uprooted small trees and damaged power lines indicate winds between 96 and 110 mph---a Category 2 hurricane on the Saffir-Simpson Scale.
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Check for extensive damage to buildings, many trees uprooted and severe power losses. The winds that did that measures between 111 and 130 mph---a Category 3 hurricane on the Saffir-Simpson Scale.
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If winds devastate buildings, destroy mobile homes, uproot most trees and disrupt power for weeks, they measure between 131 and 155 mph---a Category 4 hurricane on the Saffir-Simpson Scale.
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Winds that cause catastrophic damage---such as creating extensive building damage, blowing down small buildings, uprooting all trees and shutting down power for weeks or months---measure greater than 155 mph and qualify as a Category 5 hurricane on the Saffir-Simpson Scale.
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