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Wind Speed Rating, Beaufort Scale

Beaufort		Wind	Speed
Number	Name	MPH	Km/Hr	Description
00	Calm	<1	<1	Calm, smokes rise vertically
01	Light air	1 - 3	1 - 5	Wind direction shown by smoke, not vanes
02	Light breeze	4 - 7	6 - 11	Wind felt on face, leaves rustle, vane moves
03	Gentle breeze	8 - 12	12 - 19	Leaves, twigs moving, wind extends flag
04	Moderate breeze	13 - 18	20 - 28	Dust, loose paper raised, small branches move/
05	Fresh breeze	19 - 24	29 - 38	Small leaved trees sway, wave crests on inland waters
06	Strong breeze	25 - 31	39 - 49	Large branches move, overhead wires whistle, umbrella problematical
07	Moderate or near gale	32 - 38	50 - 61	Whole trees sway, walking against wind hard
08	Fresh gale or gale	39 - 46	62 - 74	Twigs break off trees, cars hard to steer
09	Strong gale	47 - 54	75 - 88	Light structural damage, shingles torn loose
10	Storm or whole gale	55 - 63	89 - 102	Trees uprooted, considerable structural damage
11	Storm or violent storm	64 - 72	103 - 117	Widespread damage
12	Hurricane	> 72	> 117	Widespread damage

72 mph or greater is defined as a hurricane in the U.S.

This scale was developed in 1805 by the Frenchman Francis Beaufort. He later became Hydrographer of the Navy and a Knight.