0

Below 1

Calm

Smoke rises vertically.  Leaves still.

Mirror smooth.

1

1 - 3

Light Air

Smoke drifts.

Scaly ripples

2

4 - 6

Light Breeze

Leaves rustle.  Wind felt on face.

Small wavelets.  Crests do not break.

3

7 - 10

Gentle Breeze

Light flags, leaves, and twigs move.

Large wavelets.  Crests may break.

4

11 - 16

Moderate breeze

Small tree branches move.

Small waves.  White caps.

5

17 - 21

Fresh Breeze

Small trees in motion.

Moderate waves.  Many white caps.

6

22 - 27

Strong Breeze

Large branches in motion.  Umbrellas difficult to use.

Large waves.  Foam crests.  Spray.

7

28 - 33

Moderate Gale

Whole trees move.  Pressure, walking into the wind.

White foam.  Breaking waves blown.

8

34 - 40

Fresh Gale

Branches break from trees.  Walking difficult.

Moderately high waves. Some spindrift.

9

41 - 47

Strong Gale

Slight structural damage occurs. Slate blown from roof.

Higher waves.  Dense foam.  Crests topple with spray.

10

48 - 55

Whole Gale

Trees broken.  Structural damage occurs.

Sea almost white.  Violent waves.

11

56 - 63

Storm

Widespread damage.

Exceptionally high, violent waves.  Bad visibility.

12

64+

Hurricane

Massive violence and destruction.

Sea white, much spray and foam.  Visibility seriously affected.