We are planning a trip to Yellowstone the first week in September. This is our 2nd trip to the area. The last time we went, it was in July. This time we're hoping for cooler weather and less crowds since a lot families will be back in school. Can anyone tell me what the weather will be like? Also, what will be the difference in the wildlife from our trip in July? Last time we saw a lot of buffalo, elk and bears. Are we correct in that the crowds will be down?