I think it depends a lot on what your plans are. I overnighted in Canyonlands NP in early fall. The high during the day was 100F and it does NOT cool off at night; all of that red rock just absorbs heat and then keeps it hot until probably 3-4am; it wasn’t great for camping. I plan on returning at some point and when I do it’ll be late fall.

If I wasn’t camping then it wouldn’t have been a big deal. There’s are also a few state and local parks that have similar geology, so don’t sleep on those!