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Measure Wind Speed Using The Beaufort Scale

Wind speed is measured by using a scale of 0-12 based on what you can see happening around you. It was originally developed in 1806 by Sir Francis Beaufort. In the TV weather forecasters usually use kilometers per hour to describe wind speed or they use the words in the column on the right, when sailing, the Beaufort Force scale is still used!

Beaufort
Force

Wind Speed
(KmPH)

Wind Speed
(MPH)

Clues

Terms Used in Forecasts

0

0-2

0-1

Calm; smoke rises straight up from chimneys.

Calm

1

2-5

1-3

Shown by direction of wind smoke drift, but not by wind vanes as it isn’t strong enough to make them move.

Light

2

6-12

4-7

Wind felt on face, leaves rustle; ordinary vanes moved by wind.

Light

3

13-20

8-12

Leaves and small twigs in constant motion; wind extends light flag.

Gentle

4

21-29

13-18

Raises dust and loose paper; small branches are moved.

Moderate

5

30-39

19-24

Small trees with leaves on begin to sway

Fresh

6

40-50

25-31

Large branches in motion; umbrellas used with difficulty.

Strong

7

51-61

32-38

Whole trees in motion; it’s difficult to walk against the wind.

Strong

8

62-74

39-46

Breaks twigs off trees; more difficult to walk

Gale

9

75-87

47-54

Slight damage to buildings, loose tiles may fall off roofs

Gale

10

88-101

55-63

Trees uprooted; lots of damage to buildings

Whole gale

11

102-116

64-72

Widespread damage, light building collapse

Whole gale

12

117 or more

73 or more

Houses and other buildings collapse.

Hurricane

To use this table go outside and look at the trees; are the leaves, twigs or branches moving? Look at any smoke you can see from chimneys; is it rising straight into the air? Can you feel the wind on your face? You can then use this table to help you decide on the wind speed and record it on your weather record sheet.