Hi Joanna - I'm sitting in air conditioned office at the moment, having spent last week at the Australian Open in Melbourne, which incidentally was fabulous (pity our guy lost in the final). Apparently we had a few hot days here but I imagine the temperature during the day will be somewhere between 24-28 degrees - what's that in your temperature? How quickly we forget! If you intend going out at night, I imagine you'll need a second layer - nothing too heavy though. I'll watch the weather forecast tonight and report in on Wednesday when I come back to work (that'll be your Tuesday afternoon/night).
The Harbour Bridge climb goes ahead regardless of the weather, which could be a disappointment but I'll save my dancing for the cruise and hopefully we won't have any rain next weekend!