BEAUFORT SCALE
Beaufort
Number
Name Wind Speed Description
MPH KPH
0 calm <1 <1 calm; smokes rises
vertically
1 light air 1-3 1-5 direction of wind shown
by smoke but not by
wind vanes
2 light breeze 4-7 6-11 wind felt on face; leaves
rustle; wind vane
moves
3 gentle breeze 8-12 12-19 leaves and small twigs
in constant motion;
wind extends light flag
4 moderate breeze 13-18 20-29 wind raises dust and
loose paper; small
branches move
5 fresh breeze 19-24 30-39 small-leaved trees begin
to sway; crested
wavelets form on
inland waters
6 strong breeze 25-31 40-50 large branches move;
overhead wires whistle;
umbrellas difficult to
control
7 moderate gale
or near gale
32-38 51-61 whole trees sway;
walking against wind
is difficult
8 fresh gale
or gale
39-46 62-74 twigs break off trees;
moving cars veer
9 strong gale 47-54 75-87 slight structural damage
occurs; shingles may
blow away
10 whole gale
or storm
55-63 88-102 trees uprooted;
considerable structural
damage occurs
11 storm
or violent storm
64-72 103-117 widespread damage
occurs
12 hurricane* >73 >118 widespread damage
occurs
*The U.S. uses 74 statute mph as the speed criterion for a hurricane.