Wind speed
Wind mean wind speed 10-metre wind speed
Wind speed tells you how fast air is moving. To interpret it properly, also check the measurement height, averaging period and gust speed.
Converting the units
Forecasts commonly use kilometres per hour (km/h) or metres per second (m/s). Knots are common in shipping and aviation.
- 1 m/s = 3.6 km/h.
- 10 m/s = 36 km/h.
- 1 knot is about 1.85 km/h.
Why height and time matter
For comparable surface observations, wind instruments are normally ten metres above open ground. A commonly used mean wind averages ten minutes. Gusts describe brief peaks instead. Model values at 80 or 120 metres describe a different layer of air and may be considerably higher.
A forecast example
“Westerly wind 25 km/h, gusts 45 km/h” means that air comes from the west, its mean speed is 25 km/h, and short peaks may reach 45 km/h. The values describe different aspects of the same wind. Add them together and you create wind that was never forecast.
Why your street can feel different
Trees and buildings slow or disturb the flow, while narrow gaps can accelerate it. A weather station or model cannot represent every street individually. For a bike ride, direction and gusts matter alongside the mean speed.