The Web pages for the September information and news, conditions and access and prospects and opportunities is available. I apologize for being late and not including the Labor Day holiday weekend, but events in life and problems with the Website kinda' took that away. The short story of September is that it's the transistion month from summer to fall, back to dynamic weather throughout the NP, so you have to plan, be prepared and be flexible with your trip.
September is the transistion month on every level, from summer to fall and later winter weather, from seasonal summer to fall and later winter operations, to the initial closure of roads, facilities, campgrounds, etc., and lastly when the crowds decrease significantly, especially on weekdays. But all that said, September is really the best month for photographers with the greatest diversity of opportunties minus the wildflower season ending in August this year.
Anyway, the new reports are there along with seasonal updates to the area guides and other Web pages I've long overlooked for updates. I hope they help your trip and photography work in the NP and you're always welcome to ask for help.