A scale of wind force and speed, originally devised in 1806 by Sir Francis Beaufort, a British naval officer.
Beaufort Number International Description Wind Speed (mph)
0 calm less than 1
1 light air 1-3
2 light breeze 4-7
3 gentle breeze 8-12
4 moderate breeze 13-18
5 fresh breeze 19-24
6 strong breeze 25-31
7 moderate gale 32-38
8 fresh gale 39-46
9 strong gale 47-54
10 whole gale 55-63
11 storm 64-72
12-17 hurricane 73 and above