Beaufort Number

Description

Wind Speed (m/s)

Land condition

0

Calm

<0.3

Calm. Smoke rises vertically.

1

Light air

0.3 - 1.5

Smoke drift indicates wind direction. Leaves and wind vanes are stationary.

2

Light breeze

1.6 - 3.3

Wind felt on exposed skin. Leaves rustle. Wind vanes begin to move.

3

Gentle breeze

3.4 - 5.4

Leaves and small twigs constantly moving, light flags extended.

4

Moderate breeze

5.5 - 7.9

Dust and loose paper raised. Small branches begin to move.

5

Fresh breeze

8.0 - 10.7

Branches of a moderate size move. Small trees in leaf begin to sway.

6

Strong breeze

10.8 - 13.8

Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult. Empty plastic bins tips over.

7

Near gale

13.9 - 17.1

Whole trees in motion. Effort needed to walk against the wind.

8

Gale

17.2 - 20.7

Some twigs broken from trees. Cars veer on road. Progress on foot is seriously impended.

9

Strong gale

20.8 - 24.4

Some branches break off trees, and some small trees blow over. Construction/temporary signs and barricades blow over.

10

Storm

24.5 - 28.4

Trees are broken off or uprooted, structural damage likely.

11

Violent storm

28.5 - 32.6

Widespread vegetation and structural damage likely.

12

Hurricane force

>32.7

Severe widespread damage to vegetation and structures. Debris and unsecured objects are hurled about.