We went last year the same time you are going and Sedona was hot (shorts and tee shirts, night sweatshirt), Grand Canyon started out hot until a wind storm came and then it got COLD with the wind, (shorts and tees, then shorts with sweatshirt or jeans). Needed a good windbreaker jacket. I had gloves on in momument valley. Moab was better, not hot not cool but, just comfortable in the day and the nights were cool, (shorts and tees, pants at night and a sweatshirt). Layers for Arches, start with shorts and sweatshirt then shorts and tee. Water for rafting was cold, but you do not get that wet. Your feet are in the water so you adjust pretty quickly. You'll have a wonderful time. I hope you have Tiffany and Geraldine as your guides.