Beaufort
Force

Description

mph

Specification on land

0

Calm

0

Smoke rises vertically

1

Very light

1-3

Direction of wind shown by smoke drift but not by wind vanes

2

Light Breeze

4-7

Wind felt on face, leaves rustle, ordinary wind vane moved by wind

3

Gentle Breeze

8-12

Leaves and small twigs in constant motion, wind extends light flag

4

Moderate breeze

13-18

Wind raises dust and loose paper, small branches move

5

Fresh breeze

19-24

Small trees in leaf start to sway

6

Strong breeze

25-31

Large branches in motion, telegraph wires whistle

7

Near gale

32-38

Whole trees in motion, inconvenient to walk against wind

8

Gale

39-46

Twigs break from trees, difficult to walk

9

Strong gale

47-54

Slight structural damage occurs, chimney pots and slates removed

10

Storm

55-63

Trees uprooted, considerable structural damage

11

Violent storm

64-73

Widespread damage

12

Hurricane

>74

Widespread damage