atmospheric wind wind gust 2020-05-19T21:47:51Z gust According to U.S. weather observing practice, gusts are reported when the peak wind speed reaches at least 16 knots and the variation in wind speed between the peaks and lulls is at least 9 knots. The duration of a gust is usually less than 20 seconds. An atmospheric wind which 1) has an increased rate relative to other winds in the same region and 2) is followed by a lull.