| Level
|
Windspeed (mph)
|
Windspeed (m/s)
|
Description
|
| 0
|
Calm
|
less than 1 mph (0 m/s)
|
Smoke rises vertically
|
| 1
|
Light air
|
1 – 3 mph
|
0.5-1.5 m/s
|
Smoke drifts with air, weather vanes inactive
|
| 2
|
Light breeze
|
4 – 7 mph
|
2-3 m/s
|
Weather vanes active, wind felt on face, leaves rustle
|
| 3
|
Gentle breeze
|
8 – 12 mph
|
3.5-5 m/s
|
Leaves & small twigs move, light flags extend
|
| 4
|
Moderate breeze
|
13 – 18 mph
|
5.5-8 m/s
|
Small branches sway, dust & loose paper blows about
|
| 5
|
Fresh breeze
|
19 – 24 mph
|
8.5-10.5 m/s
|
Small trees sway, waves break on inland waters
|
| 6
|
Strong breeze
|
25 – 31 mph
|
11-13.5 m/s
|
Large branches sway, umbrellas difficult to use
|
| 7
|
Moderate gale
|
32 – 38 mph
|
14-16.5 m/s
|
Whole trees sway, difficult to walk against wind
|
| 8
|
Fresh gale
|
39 – 46 mph
|
17-20 m/s
|
Twigs broken off trees, walking against wind very difficult
|
| 9
|
Strong gale
|
47 – 54 mph
|
20.5-23.5 m/s
|
Slight damage to buildings, shingles blown off roof
|
| 10
|
Whole gale
|
55 – 63 mph
|
24-27.5 m/s
|
Trees uprooted, considerable damage to buildings
|
| 11
|
Storm
|
64 – 73 mph
|
28-31.5 m/s
|
Widespread damage, very rare occurrence
|
| 12
|
Hurricane
|
over 73 mph
|
over 32 m/s
|
Violent destruction
|