回复：Yellowstone Camping

It should be warm enough by that time. I did backbacking in Yellowstone last year in mid-July, it's already summer weather by then.

Water wise, most developed campground should have water. Only a few primitive sites may not have running water. You should not worry about that.

For Grand Teton, depends on what you wanna do, 1 day may not be enough.

Cheers