Humidity is a huge factor.If I ever win the big one,I would love to move West. Northern New Mexico,Northern Arizona,Utah,etc. It still gets hot,but at 8% humidity or so,that is a relief from what I'm used to. Having lived in Southern Arizona in my teens,I didn't have a issue with the heat. Several years ago we went to South Dakota and it set a record high of 103 degrees.To me,it felt more like 78-80 because it was a dry heat. Here in the South,you walk outside and it feels like being punched in the face by a hot damp towel.
I would use a Camel Bak hydration pack,and two water bottles. Freeze the water bottles,and you'll have cold water on the way home.