About rainfall percentages 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 monthly rainfall percentages maps were based on daily rainfall data from about 6000 weather stations. The daily data were extracted from ADAM and a number of quality control checks were then applied to the data. For example, the data were checked for missing values over the length of the data record.

After the quality checks were applied to the data, monthly and seasonal averages were calculated for each of the weather stations. These were then compared to the annual averages to calculate the percentage distribution. An objective analysis technique was then applied to these station values to produce regular gridded datasets (monthly & seasonal) covering Australia.

Finally, the gridded data were visualised in a geographic information system and the colour maps created through this process.

Stations used in the analysis

Daily rainfall data from about 6000 weather stations across Australia were used to create the rainfall percentages maps. These stations are shown in the map below.

recording stations used in the monthly rainfall percentages analysis

Rainfall metadata

The following metadata summary, and detailed metadata file, provide information about the monthly and the 3-monthly gridded rainfall percentage datasets. For example, information is provided about the format, spatial extents and analysis techniques used to generate the grids.

TITLE: Mean monthly and three-monthly rainfall percentage data (base climatological data sets)
DESCRIPTION: Mean monthly and three-monthly rainfall percentage grids. The grids show the rainfall percentage 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)