A wind gust is a brief increase in wind speed. Gusts occur basically anytime the wind is blowing. Gusts are more noticeable as the wind speed increases. This is because the force exerted by the wind increases rapidly as the wind speed increases. Why do gusts occur and what causes them? Gusts occur because the air is not able to move along the ground at a uniform rate. Surface friction from vegetation, land, buildings and elevation changes slows the wind in some places more than others. The air closer to the ground is also influenced more by friction than air higher up. This creates a more turbulent wind flow along the ground and this is experienced as gusts. Higher aloft gusts are not as noticeable since the air is more smoothly flowing. This region of the atmosphere is called the free atmosphere. Close to the ground surface, the air is more turbulent and gusty. This layer is often called the friction layer or boundary layer.

Often weather reports will report the wind speed along with wind gust information. For example, wind SE 15 mph G25 mph. This is a SE wind that is averaging or typically around 15 miles per hour with gusts of up to 25 miles per hour. The typical wind gust is less than 20 seconds, thus the gusts are of shorter duration than the wind experienced when it is not gusting. Also, gusts tend to be reported if the difference between the slowest and fastest wind speed observed over several minutes is 10 miles per hour or greater. Since this is more common as overall average wind speed increases, gusts tend to be reported when it is relatively windy outside.