It would seem we have drier winters and wetter summer, in days gone by we saw little rain in summer.
Have not checked but our annual rain fall has been declining, we can't even rely on rain fall to keep our dams topped up and now rely on desal for at least 40% of our water.
Oh found this Water supply
Rainfall in south-west WA has already reduced by around 15 per cent since the mid-1970s. From 1911 to 1974 the average stream flow into Perth Dams was 338 gigalitres. From 1975 to 2000 average stream flow was almost half this value at 177 gigalitres. From 2001 to 2010 inflows again halved to approximately 75 gigalitres. There is evidence that greenhouse gases emitted by human activities are responsible for half the decline in rainfall in south-west WA.
Modelling suggests a decrease in mean annual rainfall of 7 per cent and a 14 per cent reduction in surface water runoff in the period 2021 to 2050 relative to the period 1961 to 1990. If current climate trends continue, south-west WA will potentially experience 80 per cent more drought-months by 2070.
A hotter, drier climate would inflict a high economic impact on water supply infrastructure across the country, with Perth likely to be the most severely impacted city in Australia through climate change induced water scarcity.
