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What do you understand by “gustiness”?
  • A
    It is based on an assessment of strength of variation in measured wind speed and direction.
  • B
    It can be perceived as a steady strong wind blowing from a given direction.
  • C
    It describes the frequency and strength of gusts.
  • D
    It is a very light type of turbulence.

The gust is a wind that appears suddenly at a stronger speed than the average. By definition, it is more precisely at least 5 m/s stronger than the mean wind speed and lasts only a few seconds.

Every gust will not be of the exact same strength. A gust is therefore averaged over a specific timeframe, usually 3 seconds, just as the mean wind also is an average over time - 10 minutes is the standard.

By definition, it is reported in weather messages such as METAR and TAF in the following two cases:
  • When the wind direction changes at least 30º or more while the wind speed changes at least 5 m/s (10 kt) or more.
  • When the wind speed changes at least 5 m/s (10 kt) and it is measured over two minutes or more. The WMO recommends that wind gust is determine as the average of a three-second measure.

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