Hi Hargs,
Oahu is a great spot to kite but change of season is September, little to no wind at that time of year. It's after the trades have finally stopped and before the Kona winds start. You may still get the occasional day, but for the most part, there's not much.
I used to bail around the 1st of September after teaching in Oahu all season. Tried waiting it out for the winter swells but money runs out fast when you aint working
Make sure you take a surfboard though as the first of the winter swells usually arrives in September. Get up to the north shore and ride some killer waves!
Good winds,
