Hi Tassie66, I grew up in south western NSW (Wagga) and remember the summer heatwaves that would last for weeks and almost kill us before the next one started. Likewise the winter freezing snaps! I think all our mainland states suffer from similar once you get away from the coast. A lot of our coastal towns are a bit more temperate without the extremes of our lovely western areas. We get the odd hot and humid week but Gold Coast summers sit around 28 and winter days at 20. There would be many places similar with the benefit of a nice breeze.
I'm currently on holidays in the UK and have had more aches and pains in the past 4 weeks than usual. I'm doing a lot of walking but really believe it's from the constant cold.
I think the trick is not exposing ourselves to too many extremes! Wishing you all the best with your decisions