Badlands AKA West Dakotas
Well as much as you don't think about heat when you think North Dakota I gotta say it's still a pretty brutal environment up there in the summer, and South Dakota wasn't any nicer. While the temperatures were only in the 80s most of the time the real issue is the lack of water and shade. The little Missouri in ND provided some relief if you went down to it's banks, but anywhere else was just grass, rock, and sunshine. Thankfully it still cooled off nicely at night so I could still get a good nights sleep and not wake up soaking in my own sweat.
The badlands section of these states along their western boarders is beautiful with the multi colored buttes, and the Buffalo seems to be everywhere out here again which is nice. It's also somewhat terrifying to swing around a corner on mountain roads and suddenly have to slam the brakes because there's a herd of these monsters meandering their way across the road.
I was fortunate enough to also come across several bighorn sheep climbing up and down the buttes while I was here. It's impressive how agile some of these large animals can be on rock ledges that are practically sheer.
These parks are very vehicle friendly, but not very hiker friendly. There are signs about rattle snakes at every trail head, and there aren't many trails to hike. Roughing it in the wilderness would also be difficult due to that aforementioned lack of natural water sources.
This is a must stop if you're visiting the national parks. I've never seen buttes like these anywhere else.
You can check out the immersive photos here.