Wind Vector Average Calculator
Wind is a vector, so averaging two readings means averaging their directions as well as their speeds. Simply averaging the speeds ignores how the wind shifted and overstates the steady flow. The correct method splits each wind into an east-west component and a north-south component, averages those, then recombines them into a resultant wind. Enter two wind observations as speed and the direction the wind comes from, and this calculator returns the resultant speed, resultant direction, and the wind constancy.
Vector averaging formula
u = -speed x sin(direction), v = -speed x cos(direction)
u-bar = average of u, v-bar = average of v
Resultant speed = sqrt(u-bar^2 + v-bar^2)
Resultant direction = atan2(-u-bar, -v-bar) in degrees, 0 to 360
Wind constancy = resultant speed / mean scalar speed
Direction is the meteorological from-direction in degrees. The negative signs turn each from-direction into a vector pointing downwind, which is averaged then converted back to a from-direction.
Wind averaging notes
- Resultant speed is never greater than the mean scalar speed.
- Wind constancy near 1 means a steady direction; near 0 means highly variable.
- Directions are degrees true, measured clockwise from north, as the wind comes from.
- The method generalises to any number of observations.
- Use the same speed unit for both winds; the resultant shares that unit.
Wind vector average: frequently asked questions
Why average wind as a vector instead of a number?
Wind has both speed and direction, so it is a vector. Averaging the speeds alone ignores direction and gives a misleading result, especially when winds shift. Vector averaging breaks each wind into east-west (u) and north-south (v) components, averages those, then recombines them into a resultant wind.
How are wind components defined?
Meteorological wind direction is the direction the wind comes from. For a wind of speed S from direction D, the components are u = -S x sin(D) and v = -S x cos(D), where u is the eastward component and v is the northward component. The negative signs convert from a from-direction to a vector pointing where the air goes.
How is the resultant direction found?
After averaging the u and v components, the resultant speed is the square root of (u-bar squared plus v-bar squared). The resultant from-direction is atan2(-u-bar, -v-bar) converted to degrees and wrapped into 0 to 360. This calculator handles the trigonometry for you.
What is the difference between average speed and resultant speed?
The resultant (vector) speed is always less than or equal to the average of the individual speeds, because opposing directions partially cancel. The ratio of resultant speed to average speed is the wind constancy, a measure of how steady the direction was over the period.
Can I average more than two winds?
Vector averaging extends to any number of observations: convert each to u and v, average all the u values and all the v values, then recombine. This calculator averages two observations, which is the common case for combining a pair of readings or two ends of an interval.
Official sources
- NOAA National Weather Service: JetStream Weather School.
- NOAA National Weather Service: weather.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.