Orange Whip said..
Here in Mackay, in my view, we get our best wind through winter. As John340 said, we get really good consistent south easterlies due to the ridge formed along the coast here due to the highs coming across the southern states. Generally if there's a high over SA you can expect 15-20 knots. The best flat water spot in a s/e here is Far Beach (AKA Illawong Beach). It is quite tidal hence why it is reasonably flat, you can get a good two hours either side of high tide, best when high tide is around midday. On a nepe tide you may get more than four hours sailing, water flattens out more with the outgoing tide.
Best part about sailing in winter here is the beautiful clear water and the absence of box jelly fish and the water is probably warmer than what you're used to so you may be able to get away without a wet suit.
Good luck and hope you get to experience beautiful windy Nth Qld in winter!
Crocs ?