Rainfall variability

At a glance

These rainfall variability maps provide an indication of the regularity of rainfall from one year to the next, distributed across Australia.

What do the maps show?

Rainfall variability maps show how rainfall varies from year to year. For example, if an area has lower rainfall variability, it means rainfall will tend to be more consistent from one year to the next. Many coastal areas exhibit this kind of rainfall pattern. On the other hand, higher rainfall variability means rainfall is likely to be irregular from one year to the next - heavy rainfall in some years and little or no rainfall in others. Desert areas in central Australia tend to have this kind of rainfall pattern.

There are different ways of measuring and displaying variability. These maps use the percentile analysis method for showing how rainfall varies across Australia, this is described below.

Percentile Analysis

This index of variability is defined as the 90th rainfall percentile minus the 10th rainfall percentile divided by the 50th percentile (or median). This index varies from low to extreme.

Climate maps showing a range of rainfall percentiles across Australia are available.

Further information

• About the maps - metadata and related information.
• Find out how climate statistics are calculated.
• Information about the range of gridded climate data we can provide.
• Information about additional climate products and other data available from the Bureau of Meteorology.
• Learn about the influences on the Australian climate.
• Explore other topics relating to climate education.