October is about the best time for hunting in my area of North Queensland. It will be getting a bit warm but it will be dry, the grass wont be as long so visibility is better. As water wont be so abundant, game will be centered basicly around water holes.
Around Sydney and most of Australia, the weather will be perfect for hunting. It is also pretty a pretty good time for fishing up north as well,( either North queensland or Northern Territory/Darwin )for Barramundi. See www.fishingcairns.com for fishing info.