Rainfall variability maps

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

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Annual rainfall variability

Product code: IDCJCM0009

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. The northern and desert areas in central Australia tends to have high rainfall variability during April October, though this also reflects the very low rainfall there in most years. In the south east the rainfall pattern is more or less consistent throughout the year.

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. See rainfall percentile metadata for more information.

Further information and metadata

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