Beaufort Wind Scale
Wind speed is measured by using a scale of
0-12 based on visual clues originally developed in 1806 by Sir
Francis Beaufort. He developed a rating system to make accurate
recording of wind speed. This system was developed for sailors, but
has since been modified by the National Weather Service for use on
Terms Used in NWS Forecasts
Calm; smoke rises vertically.
Shown by direction of wind smoke drift, but not by wind vanes.
Wind felt on face, leaves rustle; ordinary vanes moved by wind.
Leaves and small twigs in constant motion; wind extends light
Raises dust and loose paper; small branches are moved.
Small trees in leaf begin to sway;
crested wavelets form on inland waters.
Large branches in motion; whistling heard
in telephone wires; umbrellas used with difficulty.
Whole trees in motion; inconvenience felt
walking against the wind.
Breaks twigs off trees; generally impedes
Slight structural damage.
Seldom experienced inland; trees uprooted; considerable structural damage occurs.
Very rarely experienced inland; accompanied by widespread damage.
117 or more
73 or more
Very rarely experienced; accompanied by widespread damage.