Wind speed

One of the difficulties in describing wind is its highly variable nature. It can change in direction and strength by the second, and this must be remembered when viewing forecasts in particular.

The wind speed mentioned in forecasts and coastal observations refers to the average speed over a 10-minute period, measured at a height of 10 metres above the surface, and it’s usually given in knots(kts) or kilometers per hour.

Gusts are increases in wind speed lasting for just a few seconds. They typically range 30-40% greater than the average wind speed, but can be considerably higher in the vicinity of showers, thunderstorms and frontal systems. Squalls are similar variations in wind speed, but which last for longer periods of up to a few minutes in duration, and are sometimes produced by maritime thunderstorm activity.

In Australia, the following table summarises when warnings are issued. (all winds referred to are ten-minute average winds)