First, pack a picnic lunch with lots of cold beverages. Then suit up the kids in their swimming gear, grab the sunscreen and head for Desert Breeze Park.
Ignore the lovely lake surrounded by trees and picnic tables. Instead, head to the children's playground area. Beneath an earthen berm/overpass/observation deck are an assortment of shaded tables. This covered passageway connects a traditional playground with a "spray pad" where three dolphins and an elephant (climbing structures the rest of the year) squirt water on a cyclical timing system from May to October. Eat, chill, eat, chill -- well, you get the idea.
Repeat process as needed through mid-October.