For weeks and weeks I looked over the wind charts for "Far North Queensland" thinking of the steady stream of green arrows out of the southeast, "surely it can't be that good!" An eventual phone call to a kite school "somewhere north of Cairns" would soon follow where I'd be told straight up, "Yep, it's that good and if you come, leave your 15 meter at home" and that, at 90 kilos I'd only need my 12 and 9 meter kites. Still I was skeptical so pack a 15 and 12 I did. Now, back from a somewhat pricey 5 day get away I'm here to say, Thank Christ I did!!!!! Had I not listened to that little voice in my head, I'd have had all of an hour or two of riding the entire time. Thanks to the 15 my riding time was respectable but it was a flukey and, more times than not, very frustrating sort of wind. If you weren't camped out with kites primed and ready,chances were good you'd miss the windows.
From various individuals that have been north of Cairns for weeks and months I quickly learned this was par for the course and that the wind guage for the Cairns reading is out on the Low Isles, a good 14 kilometers offshore from Port Douglas. Apparently this was a slight improvement from when the even more distant Green Isle was used. While the "Green Arrow Congo Line" had been plastered across my computer screen for weeks, I was assured it had been pretty hit or miss in the wind department where I was. Many of the same people let it be known in no uncertain terms that certain areas north of Cairns are hardly the wind machine factory that certain kite schools in the area would have you believe.
I understand (though don't agree with) why kite schools run with the notion of their area being a kiter's paradise. What I'm wondering is why can't a wind guage closer to the actual listed destination be used?

Cairns has one of the most exagerated wind forecasts in Australia. The rule of thumb is whatever Seabreeze says for Four Mile Beach take 5 knots off. For Yorkeys Knob take 10 to 12 knots off the forecast. I can count on one hand the number of days above 20 knots in the past year. This year we've had little wind at Yorkey's. Winds have been very southerly with short bursts of 10 - 15 knots for 1/2 an hour. Saying that, Yorkey's when it's windy is one of the best places to kite in Australia. I've seen seasons start like this before. Then suddenly its windy as hell and onshore. If you come to Cairns bring a 12m/10m for medium/lightweights and 14/16m for heavyweights.
As a Cairns local, this year I have spent most of my kiting days at Four Mile Beach in Port Douglas. It has had more consistent windy days but still with many windless spells in between, frustrating not just visitors but the locals as well.
If you come to Nth Qld always pack your light wind gear!

I went to Cairns and Port Douglas about 2 weeks ago and kited 3 out of the four days I was there. I think I was quite lucky on timing the wind. The first day I kited Yorkey's and had about 18 to 20 knots. I kited Port Douglas the next day and had better conditions again, but a couple of guys there said the day previous for them was slack and unkiteable at Port Douglas when Yorkey's was good. There is only 60km's of coastline between the two spots and the wind conditions can be very different.

The wind gauge for Cairns is at the Cairns airport and is usually quite accurate. The biggest problem for Cairns (Yorkey's Knob) is the headlands that surround the area. As soon as there is any large build up of cloud or rain in the around the headlands our inshore wind seems to disappear. It has been another wet year and yet again we have good wind forecast only to be let down. Frustrating as only a few kms offshore it will be blowing its ring out.

Port Douglas is usually far more consistent and often see Cairns locals heading up there for a kite as there is simply no wind in Cairns.

If you are contemplating a kiting holiday up here I would contact Ant from Australian Kitesurfaris and get on one of his trips. They kite well north of Cairns (up near cooktown) and always have good wind. Most guys are on 7m/9m most of the time and I have not known them to ever miss out on wind.

Cairns can be a fickle spot to say the least.

Having lived in Port as a kiter for 5 years i can attest the frustrating nature of the wind there, especially it seems, if its cloudy. The wind tends to push through much better on clear days.
Head north of Cape Trib, different ball game entirely. In fact the bureaue lists Cooktown as the consistently windiest Town in Australia and some spots further north are even windier. Unlike Cairns-Port if the forecast says 20-25 for Cooktown it will probably blow 27 or 28 knots. Whereas (as someone has already said) the same forecast for Cairns-Port will most often produce less than 15 Knots.