A wind gust is defined as a wind peak exceeding the previous 10-minute mean speed by at least 10 knots (18 km/h). METARs report gusts with the "G" indicator: 25G40KT = mean 25 knots, gusts 40.
The most destructive gusts occur in thunderstorm gust fronts, microbursts, and channelled winds (cierzo, tramontana). The gust-to-mean ratio (gust factor) is higher over rough terrain (cities: 1.5–2×) than over open sea (1.2–1.4×).