Historical rainfall maps for the South West Land Division

Page last updated: Wednesday, 31 January 2024 - 2:59pm

Historical rainfall decile maps for the South West Land Division (SWLD) are provided using the baseline period 1975 to 2023.

This baseline time period is used because since the mid-1970s, rainfall in the two wettest months of June and July in the SWLD has declined by up to 20%, with reductions in the number of rain days and the rainfall amounts in extreme events (IOCI, 2012). The reason winter rainfall has declined is attributed to fewer days with low pressure weather systems and the persistence of high pressure systems (IOCI, 2012).

Since 2000, the overall trend in rainfall is for more drier seasons (decile 1-3) than wetter (decile 8-10).

Total rainfall maps:

Rainfall decile maps:

  • Four seasons based on the Gregorian calendar:
  • Six seasons based on the Noongar calendar:
    • Birak (December to January) – hot and dry with easterly winds during the day
    • Bunuru (February to March) – hottest time of the year with hot easterly and north winds, with little to no rain
    • Djeran (April to May) – becoming cooler with winds from the south-west
    • Makuru (June to July) – coldest and wettest time of the year
    • Djilba (August to September) – very cold and clear days, becoming warmer 
    • Kambarang (October to November) - longer dry periods, rain decreasing.

Thanks to South West Aboriginal Land and Sea Council for their support.

IOCI (2012) milestone report 4 Project 1.2 south-west Western Australia’s regional surface climate and weather systems. (accessed 21 August 2019)

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Author

Meredith Guthrie