Beaufort Scale

Beaufort Number Name Miles per Hour Description
0 calm < 1 smoke rises vertically
1 light air 1 - 3 direction of wind shown by smoke but not wind vanes
2 light breeze 4 - 7 leaves rustle
3 gentle breeze 8 - 12 leaves and small twigs in constant motion
4 moderate breeze 13 - 18 small branches move
5 fresh breeze 19 - 24 small trees begin to sway; crested wavelets form on inland waters
6 strong breeze 25 - 31 large branches in motion; umbrellas used with difficulty
7 near gale 32 - 38 whole trees in motion; inconvenient walking into wind
8 gale 39 - 46 twigs break off trees; walking progress impeded
9 strong gale 47 - 54 slight structural damage occurs
10 storm 55 - 63 trees uprooted; considerable structural damage
11 violent storm 64 - 72 widespread damage
12 hurricane 73 - 136 devastation