Early May can be really cool or really hot. Been there when it was nearly freezing and when it was over 100. April & May are big event / rally months and campsites in Campground (with or without service) can be a challenge to find and rates are at prime season rates. Always somewhere to boondock but many of the good spots closer to town again will be taken. Both North & South of Moab have primitive boondocking you can fit in.
rocmoc n AZ