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sustained wind The average wind over a 1-minute interval. When the weather report calls for 20 knots of wind, they do not mean gusts to 20, but rather a significant occurrence of sustained winds of 20 knots — that is, when you average the wind speed over a 1-minute interval it will be 20 knots or greater. The next step up in forecasting is typically 25 knots, so "20" = 18 to 22, "25" = 23 to 27, etc. In Australia and much of the rest of the world, the definition of sustained is a 10-minute average, but this definition is often clarified when used. When ships taking part in the U.S. Voluntary Observing Ship program report winds that are later used to prepare weather maps, they also use a 10-minute average. They often refer to this as the "mean wind speed" and they usually imply that it is the wind at an elevation of 10 meters. On the other hand, when warnings are issued for gale, storm, hurricane or small craft advisory they refer to "sustained" winds or conditions and in this case sustained means lasting at least 2 hours.

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