As others will tell you, it all depends! 3 of our 4 Ystone trips have been in the fall--after Sept 1. We enjoyed them all--knowing that several Ystone lodges will be closed but the animals don't visit them so we still saw lots of animals! Just had easy to handle crowds and parking was not an issue. What did we miss?? Others who went in June said the flowers were great and the young animals were out and great to see. Our last trip to Ystone was in the winter--it was really great and definitely not crowded. We stayed in Fishing Bridge and West Yellowstone on our fall trips. Both worked for our 38 foot fifth wheel. Have a great trip!