| Force |
Speed |
Name |
Conditions
at Sea |
Conditions
on Land |
|
knots |
km/h |
m/s |
|
0 |
< 1 |
< 2 |
< 0.5 |
Calm |
Sea like a mirror. |
Smoke rises vertically. |
|
1 |
1-3 |
1-5 |
0.5-1.5 |
Light air |
Ripples only. |
Smoke drifts and leaves rustle. |
|
2 |
4-6 |
6-11 |
1.5-3 |
Light breeze |
Small wavelets (0.2m). Crests have a
glassy appearance. |
Wind felt on face. |
|
3 |
7-10 |
12-19 |
3-5 |
Gentle breeze |
Large wavelets (0.6m), crests begin to
break. |
Flags extended, leaves move. |
|
4 |
11-16 |
20-29 |
5-8 |
Moderate breeze |
Small waves (1m), some whitecaps. |
Dust and small branches move. |
|
5 |
17-21 |
30-39 |
8-11 |
Fresh breeze |
Moderate waves (1.8m), many whitecaps. |
Small trees begin to sway. |
|
6 |
22-27 |
40-50 |
11-14 |
Strong breeze |
Large waves (3m), probably some spray. |
Large branches move, wires whistle,
umbrellas are difficult to control. |
|
7 |
28-33 |
51-61 |
14-17 |
Near gale |
Mounting sea (4m) with foam blown in
streaks downwind. |
Whole trees in motion, inconvenience in
walking. |
|
8 |
34-40 |
62-74 |
17-21 |
Gale |
Moderately high waves (5.5m), crests break
into spindrift. |
Difficult to walk against wind. Twigs and
small branches blown off trees. |
|
9 |
41-47 |
76-87 |
21-24 |
Strong gale |
High waves (7m), dense foam, visibility
affected. |
Minor structural damage may occur
(shingles blown off roofs). |
|
10 |
48-55 |
88-102 |
24-28 |
Storm |
Very high waves (9m), heavy sea roll,
visibility impaired. Surface generally white. |
Trees uprooted, structural damage likely. |
|
11 |
56-63 |
103-118 |
28-33 |
Violent storm |
Exceptionally high waves (11m), visibility
poor. |
Widespread damage to structures. |
|
12 |
64+ |
119+ |
33+ |
Hurricane |
14m waves, air filled with foam and spray,
visibility bad. |
Severe structural damage to buildings,
wide spread devastation. |
