What classifies as “variable” winds

In the METAR for an airport you may see VRB or V listed in the meteorologic information. The definition can vary by country, but there is a standardized definition put out by the International Civil Aviation Organization.

V: More than 6 km/h and variation less than 180°. Mean wind direction and variation. Annex 3, § 4.1.5.2:

“1) when the total variation is 60° or more and less than 180° and the wind speed is 6 km/h (3 kt) or more, such directional variations shall be reported as the two extreme directions between which the surface wind has varied”

E.g. 31015G27KT 280V350.

VRB: Less than 6 km/h or variation more than 180°. No mean wind direction. Annex 3, § 4.1.5.2:

“2) when the total variation is 60° or more and less than 180° and the wind speed is less than 6 km/h (3 kt), the wind direction shall be reported as variable with no mean wind direction; or

3) when the total variation is 180° or more, the wind direction shall be reported as variable with no mean wind direction”

E.g. VRB02KT