I'll just add that I've attended a conference at the University of Adelaide, in August. The weather was very pleasant throughout my stay, with conditions similar to the end of Spring in the south of the UK.
Thank you all for your replies, I do actually prefer winter temperatures as I'm not a fan of the heat, just wondered how cold to expect. Due to my job being term-time only I am tied to travelling on certain dates but I'm staying with a friend over there so should be OK.