Wind Speeds - Beaufort Scale


Beaufort number

Description

Wind speed

Land conditions

0

Calm

< 1 km/h

Calm. Smoke rises vertically.

< 1 mph

< 1 knot

< 0.3 m/s

1

Light air

1–5 km/h

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

1–3 mph

1–3 knots

0.3–1.5 m/s

2

Light breeze

6–11 km/h

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

4–7 mph

4–6 knots

1.6–3.3 m/s

3

Gentle breeze

12–19 km/h

Leaves and small twigs constantly moving, light flags extended.

8–12 mph

7–10 knots

3.4–5.5 m/s

4

Moderate breeze

20–28 km/h

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

13–18 mph

11–16 knots

5.5–7.9 m/s

5

Fresh breeze

29–38 km/h

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

19–24 mph

17–21 knots

8–10.7 m/s

6

Strong breeze

38–49 km/h

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

25–31 mph

22–27 knots

10.8–13.8 m/s

7

High wind,

moderate gale,

near gale

50–61 km/h

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

32–38 mph

28–33 knots

13.9–17.1 m/s

8

Gale,

fresh gale

62–74 km/h

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

39–46 mph

34–40 knots

17.2–20.7 m/s

9

Strong/severe gale

75–88 km/h

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

47-54 mph

41–47 knots

20.8–24.4 m/s

10

Storm,[7]

whole gale

89–102 km/h

Trees are broken off or uprooted, structural damage likely.

55–63 mph

48–55 knots

24.5–28.4 m/s

11

Violent storm

103–117 km/h

Widespread vegetation and structural damage likely.

64–72 mph

56–63 knots

28.5–32.6 m/s

12

Hurricane force [7]

≥ 118 km/h

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

≥ 73 mph

≥ 64 knots

≥ 32.7 m/s

References: Met Office,[8] Royal Meteorological Society,[9] Encyclopædia Britannica[10]



Comments