I am leaving September 15 for a 10 day stay in these 2 parks. Has there been any problem with forest fires/smoke in these areas?

Thanks for your replies!

I've been checking also. There are some daily reports at:

http://www.yellowstone-natl-park.com/wwwboard/chat2.htm

Also, check out:

http://www.yellowstone.net/forums/index.php

Things change pretty much daily out there, but those two places are the best I've found to get first hand information.

There is presently a fire near one of the entrances to Yellowstone.

Google the parks and they both have official govt websites that have info on lots of things.

What will be happening in September?
No one knows. If you call the parks reservation services, the people often live in or near the parks.

I got info on the entrance that was temporarily closed from someone there. There is more than one entrance to Yellowstone, so the park itself (or part of it)was not closed (as of this AM).

Also, google "Yellowstone fire" for info.

Best wishes for a great trip.

Click on the NPS Morning Report Scroll down past to the incidents to NPS Fire News, they normally post the current fire situation daily.

http://www.nps.gov/news/index.htm

Thanks to everyone for their replies.