High winds rarely cause issues for airlines on the ground. When there are thunderstorms in the vicinity, flights may be delayed to avoid encountering sudden and abrupt changes in wind speed and direction, known as wind shear. When it's especially windy, airports may temporarily close crosswind runways because airplanes have trouble accelerating or decelerating when buffeted by winds blowing sideways, and the distances required for taking off and landing increase when an aircraft is heading against the wind. If there's snow on the ground, high winds may cause it to blow and drift across runways, resulting in flight delays.
During mid-flight, high winds aloft often cause turbulence. While some passengers grow nervous when their airplane flies erratically, there is little danger associated with turbulence, so long as fliers remain seated and buckled in. Airplanes are built to withstand stresses far stronger than those encountered during most turbulent episodes, and pilots are trained to avoid dangerous thunderstorms. Turbulence caused by high winds is most common at higher altitudes and on flight paths near the current jet stream.
Wind shear is a sudden and powerful change in wind direction, most often associated with microbursts -- strong downdrafts that occur frequently during thunderstorms. The downdraft creates a strong headwind that will cause a corresponding increase in airspeed; if the pilots don't recognize this is a result of wind shear, they may overcompensate by reducing engine power. When the plane passes through the downdraft, it encounters a tailwind, which will cause the aircraft to lose airspeed and, as a result, altitude. Airplanes are most vulnerable to wind shear during takeoffs and landings.
Commercial airlines frequently encounter headwinds and tailwinds. Headwinds occur when an airplane is flying against the direction of the wind, leading to a longer flight. Tailwinds occur when the winds are blowing in the same direction the aircraft is flying, cutting down on the overall flying time. Headwinds and tailwinds also have an effect on takeoffs and landings. Airplanes fly based on airspeed rather than ground speed; the stronger the headwind, the shorter the distance required to travel down the runway to reach the proper airspeed. Conversely, a tailwind will make the ground speed faster but have no effect on the airspeed.
