Wind Roses

Across Australia, wind speed and wind direction measurements are made at various times of the day. Historically, these measurements tended to occur at 9am and 3pm, although some locations (mostly sites within cities and at airports) had more extensive observation programs. More recently, the introduction of Australia's Automatic Weather Station (AWS) network has allowed the frequency of observations to increase, in many cases to eight or more observations per day.

Wind roses summarise the occurrence of winds at a location, showing their strength, direction and frequency. The wind roses available on this web site are based on at least 15 years of records, and have been created for the more common 9am and 3pm observation times.

Interpreting the wind rose

There are a number of different formats which can be used to display wind roses. These wind roses have been constructed in the following way:

• The percentage of calm conditions is represented by the size of the centre circle - the bigger the circle, the higher is the frequency of calm conditions.
• Each branch of the rose represents wind coming from that direction, with north to the top of the diagram. Eight directions are used.
• The branches are divided into segments of different thickness and colour, which represent wind speed ranges from that direction. Speed ranges of 10km/h are used in these wind roses. The length of each segment within a branch is proportional to the frequency of winds blowing within the corresponding range of speeds from that direction.

Last modified 20 October 2004