The Beaufort Wind Strength Scale

This table is taken from 'Pocket Ref' by Thomas J. Glover, Sequoia Publishing. ISBN 1-885071-00-0
© 1996–97 by Thomas J. Glover
2nd Edition, 13th printing - September 1997.
A highly recommended pocket reference.
If this book came with a roll of duct tape and a can of WD40 my toolkit would be complete!

Beaufort Number or Force	Wind Speed Knots (Miles/Hour) [km/Hour]	Description
0	0 – 1 (<1) [<2]	Calm: Sill. Smoke will rise vertically. The sea is mirror smooth.
1	1 – 3 (1 – 3) [2 – 6]	Light Air: Rising smoke drifts, weather vane is inactive. Scale-like ripples on sea, no foam on wave crest.
2	4 – 6 (5 – 7) [7 – 11]	Light Breeze: Leaves rustle, can feel wind on your face, weather vane is active. Short wavelets, glassy wave crests.
3	7 – 10 (8 – 12) [13 – 19]	Gentle Breeze: Leaves and twigs move around. Light weight flags extended. Long wavelets, glassy wave crests
4	11 – 16 (13 – 18) [20 – 30]	Moderate Breeze: Moves thin branches, raises dust and paper. Fairly frequent whitecaps appear.
5	17 – 21 (20 – 24) [31 – 39]	Fresh Breeze: Small trees sway. Moderate waves, many white foam crests.
6*	22 – 27 (25 – 31) [41 – 50]	Strong Breeze: Large tree branches move, open wires begin to "whistle", umbrellas are difficult to control. Some spray on the sea surface.
7	28 – 23 (32 – 38) [52 – 61]	Moderate Gale: Large trees begin to sway, noticeably difficult to walk. Foam from waves blown in streaks.
8	34 – 40 (39 – 46) [63 – 74]	Fresh Gale: Small branches broken from trees, walking in wind is very difficult. Long streaks of foam appear on sea.
9	41 – 47 (47 – 54) [76 – 87]	Strong Gale: Slight damage occurs to buildings, shingles are blown off roofs, High waves, crests start to roll over.
10	48 – 55 (55 – 63} [89 – 102]	Whole Gale: Large trees are uprooted, building damage is considerable. The sea takes on a white appearance.
11	56 – 63 (64 – 72) [104 – 117]	Storm: Extensive widespread damage. Exceptionally high waves, visibility affected.
12	64+ (>74) [>119]	Hurricane: Extreme destruction. Storm waves at sea. Air is filled with spray and foam.

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