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:
- Annual (January to December)
- May to October
- November to March.
Rainfall decile maps:
- Annual (January to December)
- April to October
- May to October - also see additional information about the signficant climate driver that season
- November to March.
- 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)