About annual, seasonal and monthly rainfall maps

How were the maps created?

Rainfall data are recorded at a network of weather stations across Australia. The data from these weather stations are stored electronically in the Bureau of Meteorology's database called ADAM (Australian Data Archive for Meteorology).

The average rainfall maps were based on quality controlled monthly rainfall data, sourced from ADAM, and spatially analysed using a technique known as statistical interpolation. The resulting analysed monthly rainfall data is called the Australian Gridded Climate Dataset (AGCD).

These maps show the average annual, seasonal and monthly rainfall over the period 1991 to 2020. For each month, a monthly average is calculated using 30 years of monthly data between 1991 and 2020. Seasonal and annual averages are calculated using the contributing monthly averages. For instance, when calculating a summer (December to February) climate average, a three-month average is formed from 1991-2020 average for December, January and February data separately, and then averaged again over the three-month period.

Finally, the gridded data were mapped using the same mapping system used in the operational gridded rainfall product.

Rainfall metadata

The following metadata summary, and detailed metadata file, provide information about the average monthly, seasonal and annual gridded rainfall datasets. For example, information is provided about the format, spatial extents and analysis techniques used to generate the grids.

TITLE: Mean monthly, seasonal and annual rainfall data (base climatological data sets)
DESCRIPTION: Mean monthly, seasonal and annual rainfall grids. The grids show the rainfall values across Australia in the form of a two-dimensional array. The mean data are based on the standard 30-year period 1991–2020.
CUSTODIAN: Bureau of Meteorology
AVAILABLE FORMAT TYPE(S): ASCII row major, NetCDF, Shapefiles (upon request).
SCALE/RESOLUTION 0.05°/5 km; 0.01°/1 km (upon request)