BEAUFORT SCALE
BEAUFORT
NUMBER
NAMEWIND SPEEDDESCRIPTION
MPHKPH
0calm<1<1calm; smokes rises
vertically
1light air1-31-5direction of wind shown
by smoke but not by
wind vanes
2light breeze4-76-11wind felt on face; leaves
rustle; wind vane
moves
3gentle breeze8-1212-19leaves and small twigs
in constant motion;
wind extends light flag
4moderate breeze13-1820-28wind raises dust and
loose paper; small
branches move
5fresh breeze19-2429-38small-leaved trees begin
to sway; crested
wavelets form on
inland waters
6strong breeze25-3139-49large branches move;
overhead wires whistle;
umbrellas difficult to
control
7moderate gale
or near gale
32-3850-61whole trees sway;
walking against wind
is difficult
8fresh gale
or gale
39-4662-74twigs break off trees;
moving cars veer
9strong gale47-5475-88slight structural damage
occurs; shingles may
blow away
10whole gale
or storm
55-6389-102trees uprooted;
considerable structural
damage occurs
11storm
or violent storm
64-72103-117widespread damage
occurs
12hurricane*>72>117widespread damage
occurs
*The U.S. uses 74 statute mph as the speed criterion for a hurricane.