On a windy day like today, it is can be helpful to know the difference between a wind gust and the sustained wind speed.
A Sustained Wind is found by averaging observed values of the wind over a two minute period.
Wind Speed is defined by the National Weather Service as a snapshot of the sustained wind speed in knots valid for the indicated hour.
Wind Gusts is defined by the National Weather Service as a quick and sudden increase in the speed of wind. Wind gusts can be caused by friction, wind shear, or by heating. A wind gust usually lasts less than 20 seconds.
To properly report an observed wind gust, it needs to be reported when the peak wind speed reaches 16 knots (18 mph) and the variation in the wind speed between the peak and lull is at least 9 knots (10 mph).
To recap, the sustained wind is the average wind speed over an amount of time, while the wind gust is when there is a faster burst of wind for a short amount of time.