We find a place with a water feature where the kids can cool off. Our zoo has one that's nice. I know when we lived in Killeen there was a free park in Belton that was all water. It was great!
We always love visiting the library.
Free days at museums and zoos.
Check out local parks & recs for activities.
HTH. My ds is going to camp next month, so I'm brainstorming things to do with my dd.