Beaufort

Beaufort Number *** Wind Speed in Miles/hour (Km/hour) *** Description

• 0 *** <1 (<1.6)***Calm Still: Smoke will rise vertically.
• 1***1-3(1.6-4.8)*** Light Air: Rising smoke drifts, weather vane is inactive.
• 2***4-7(6.4-11.3)***Light Breeze: Leaves rustle, can feel wind on your face, weather vane is inactive.
• 3***8-12(12.9-19.3)***Gentle Breeze: Leaves and twigs move around. Light weight flags extend.
• 4***13-18 (20.9-29.0)***Moderate Breeze: Moves thin branches, raises dust and paper.
• 5***19-24 (30.6-38.6)***Fresh Breeze: Moves trees sway.
• 6***25-31(40.2-50.0) ***Strong Breeze: Large tree branches move, open wires (such as telegraph wires) begin to "whistle", umbrellas are difficult to keep under control.
• 7***32-38 (51.5-61.2)***Moderate Gale: Large trees begin to sway, noticeably difficult to walk.
• 8***39-46(62.8-74.0)***Fresh Gale: Twigs and small branches are broken from trees, walking into the wind is very difficult.
• 9***47-54(75.6-86.9)***Strong Gale: Slight damage occurs to buildings, shingles are blown off of roofs.
• 10***55-63 (88.5-101.4)***Whole Gale: Large trees are uprooted, building damage is considerable.
• 11***64-72 (103.0-115.9)***Storm: Extensive widespread damage. These typically occur only at sea, and rarely inland.
• 12***>73 (>115.9)***Hurricane: Extreme destruction.

NOTE: The Beaufort number is also referred to as a "Force" number, for example,

"Force 10 Gale".

* To calculate knots, divide miles/hour by 1.15.

* Small craft advisories are usually issued when force 6 is reached.

Books on weather and the sea:

• The Island Light A picture book for fun
• We Didn't Mean to go to Sea The Walker children are swept out to see in an unfamiliar boat--alone!
• The Boy Who Sailed Around the World Alone (out of print--check your library)
• Brendan the Navigator My kids actually fought over this history book!
• Hurricane and Tornado An Eyewitness book
• The Cloud Book A nifty little book from Tomie De Paola
• Storms A Seymour Simon book

Back to Autumn