How to Measure Wind Speed Beaufort Wind Force Scale | The Old Farmer's Almanac

How to Measure Wind Speed: The Beaufort Wind Force Scale

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Below is a wind chart, created in 1805 by Admiral Beaufort of the British Navy. Beaufort arranged the numbers 0 to 12 to indicate the strength of the wind from calm (force 0) to hurricane (force 12). Here’s a wind force scale adapted to land.

“Used Mostly at Sea but of Help to All Who Are Interested in the Weather”

Wind Force Scale

Beaufort Force Description When You See or Feel This Effect Wind (mph) Wind (km/h)
0 Calm Smoke goes straight up less than 1 less than 2
1 Light air Wind direction is shown by smoke drift but not by wind vane 1-3 2-5
2 Light breeze Wind is felt on the face; leaves rustle; wind vanes move 4-7 6-11
3 Gentle breeze Leaves and small twigs move steadily; wind extends small flags straight out 8-12 12-19
4 Moderate breeze Wind raises dust and loose paper; small branches move 13-18 20-29
5 Fresh breeze Small trees sway; waves form on lakes 19-24 30-39
6 Strong breeze Large branches move; wires whistle; umbrellas are difficult to use 25-31 40-50
7 Near gale Whole trees are in motion; walking against the wind is difficult 32-38 51-61
8 Gale Twigs break from trees; walking against the wind is very difficult 39-46 62-74
9 Strong gale Buildings suffer minimal damage; roof shingles are removed 47-54 75-87
10 Whole gale (Storm) Trees are uprooted 55-63 88-101
11 Violent storm Widespread damage 64-72 102-116
12 Hurricane Widespread destruction 73+ 117+