late season - stream water low, snow mostly gone except for a few patches near the high passes, where trails will be dug in deep if there's any snow left on the actual trail.
Bugs usually are dead by mid September as it freezes at night quite regularly up there. Bring a warmer sleeping bag - 10F or so should do. Expect a lot of hikers - all those who want to beat the "summer crowds" are there in September.
Days are shorter, so plan on using a headlight around camp much more than in summer. Extra batteries may be useful.
