The Beaufort Scale of wind speeds was devised in 1805 by Sir Francis Beaufort and is still in use today.  It is used to estimate wind speeds by direct observation of common objects

    The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land.  Its full name is the Beaufort Wind Force Scale, although it is a measure of wind speed and not of force.   The scale was devised in 1805 by Rear Admiral Sir Francis Beaufort, an Irish Royal Navy officer.   In the early 19th century, naval officers made regular weather observations, but there was no standard scale and could be very subjective – one man's "stiff breeze" might be another's "soft breeze".   Sir Beaufort succeeded in standardizing the scale.

    The initial Beaufort Number descriptions related wind conditions to effects on the sails of a frigate, then the main ship of the Royal Navy.   In 1916, to accommodate the growth of steam power, the descriptions were changed to how the sea, not the sails, behaved and extended to land observations.


Beaufort Number
or Force

Wind Speed


Effects on Land and Sea







Still, calm air, smoke will rise vertically

Water surface is mirror-like


1 to 3

1 to 3

Light Air

Rising smoke drifts, wind vane is inactive

Small ripples appear on water surface


4 to 7

4 to 6

Light Breeze

Leaves rustle, can feel wind on your face, wind vanes begin to move

Small wavelets develop, crests are glassy


8 to 12

7 to 10

Gentle Breeze

Leaves and small twigs move, light weight flags extend

Large wavelets, crests start to break, some whitecaps


13 to 18

11 to 16

Moderate Breeze

Small branches move, raises dust, leaves and paper

Small waves develop, becoming longer, whitecaps


19 to 24

17 to 21

Fresh Breeze

Small trees sway

White crested wavelets (whitecaps) form, some spray


25 to 31

22 to 27

Strong Breeze

Large tree branches move,  telephone wires begin to whistle, umbrellas are difficult to keep under control

Larger waves form, whitecaps prevalent, spray


32 to 38

28 to 33

or Near Gale

Large trees sway, becoming difficult to walk

Larger waves develop, white foam from breaking waves begins to be blown


39 to 46

34 to 40


Twigs and small branches are broken from trees, walking is difficult

Moderately large waves with blown foam


47 to 54

41 to 47

Strong Gale

Slight damage occurs to buildings, shingles are blown off of roofs

High waves (6 meters), rolling seas, dense foam. Blowing spray reduces visibility


55 to 63

48 to 55


Trees are broken or uprooted, building damage is considerable

Large waves (6-9 meters), overhanging crests, sea becomes white with foam, heavy rolling, reduced visibility


64 to 72

56 to 63

Violent Storm

Extensive and widespread damage

Large waves (9-14 meters), white foam, visibility further reduced


> 73

> 64


Extreme destruction and devastation

Large waves over 14 meters, air filled with foam, sea white with foam and driving spray, little visibility