I agree with the previous suggestions. We are also living not far from Lane Cove. Betwen about 10am and 3pm it is so warm at the moment that I have been just getting around in a 3/4 tshirt and jeans and my DS in a long sleeved t.shirt, singlet, long pants, socks and shoes. If you are in the sun but out of the wind it seems unseasonably warm at the moment. I head out with a zip up jumper and/or sleeveless fleecey vest in my bag for DS and a jumper/jacket for me in case we end up out of the sun and in the wind and more layering is needed. Also for some reason it seems much warmer outside in the middle of the day than inside. Must be the sun factor... So if you are going to spend lots of time indoors, perhaps your son will need to wear a spencer as well. No matter what you will definitely need warmer clothes (eg jumper/cardie) for early morning and late afternoon and overnight warm bedding/pj's/sleeping bag etc.