September is getting towards the end of the season for trade winds, but still there are plenty of good kiteable days. See Brett at Windswell (school at the southern end of Fourmile Beach) for info on downwinders, island and reef sessions.
The closest you will get to waves is at Wonga beach where the shore profile and angle of the beach gives you OK waves and mostly onshore winds. On a good day it can get to overhead out the back.
The major issue with waves is the Great Barrier Reef - the "best" surf beach in the Cairns-PD region is called Rat Sh!t bay for good reason.

hey mate, I was up there from july til december last year, and never found what most people would call decent waves, its all flat water, merky, tidal puss, some of the locals are cool, brett and the team are good value, but dont ride down towards Cairns, theres a bit of attitude down there! I did hear that the boys boat out to the reef and ride, but I dont think its for the waves, just the better coloured water, KiteRite is the only shop up that way, and there really good for advice, there at Yorkeys Knob down towards Cairns- Give'm a call or email and they'll heap ya out-
cheers

Boxburg has hit the nail on the head with Wonga. When the SEasterly picks up Wonga gets up to head high waves and they line up nicely. Unfortunately the water is always brown but hey can't have it all. Wonga is about 30 mins past Port.

I kite in Cairns and I don't think we have a real attitude problem but that's from an insider looking out.

Camo