Wind speed is the speed of the air relative to the ground. Usually, only the horizontal speed is considered.
More precisely, the wind speed is usually measured with a small rotating wind meter, the cup cross anemometer.
| Symbol | Beschreibung | Geschw. in km/h | in Knoten |
 | Windless | 0-1 | 0 |
 | Light air | 2-9 | 1-5 |
 | Light breeze | 10-19 | 6-10 |
 | Gentle breeze | 20-28 | 11-15 |
 | Moderate breeze | 29-37 | 16-20 |
 | Fresh breeze | 38-46 | 21-25 |
 | Strong breeze | 47-56 | 26-30 |
 | High wind | 57-65 | 31-35 |
 | Gale, frash gale | 66-74 | 36-40 |
 | Strong, severe gale | 75-83 | 41-45 |
 | Storm | 84-93 | 46-50 |
 | Whole gale | 94-102 | 51-55 |
 | Violent Storm | 103-111 | 56-60 |
 | Hurricane | 112-120 | 61-65 |
| Hurricane | 121-130 | 66-70 | |
| Hurricane | 131-139 | 71-75 | |
| Hurricane | 140-149 | 76-80 | |
| Hurricane | 150-157 | 81-85 | |
| Hurricane | 158-167 | 86-90 | |
| Hurricane | 168-176 | 91-95 | |
 | Hurricane | 177-185 | 96-100 |
 | Hurricane | 186-194 | 101-105 |
Wind speed is expressed in kilometers per hour, meters per second, knots, or miles per hour.
When wind speeds are not indicated by their measured value, they are usually classified according to the Beaufort scale, which is indicated by the use of the terms wind force (e.g. 5) or Beaufort (e.g. 5).