Yellowstone is on a small mountain so the elevation is moderately high. We were not prepared for snow in July. It did not stick well, but the temperate was near freezing. Hours later it was nice again.
Edit: Not OP, just wanting to point out that snow is on the ground most of the year in the higher parts of Yellowstone.
Bison! And yes there are still some in the US. Not as many as there used to be in the 1800’s, but there are still quite a number of them around the country.