When I was a kid I lived in an old Victorian house with no central AC. We had an AC in the kitchen and Mom and Dad had an AC in their bedroom, but that was it.
Because of that, we had a LOT of cold evening meals in the summer -- pasta salads, chicken or tuna salad, straight salad, even jello salads filled with vegetables, olives (yuk!), chicken, etc.
Anyway, despite the jello hell, some of that rubbed off on me and when it's really hot and humid I'll often make either cucumbers with curried chicken salad or I'll take a nice, vine ripe tomato, cut out the center, and stuff it with chicken or tuna salad.
One of the hardest things about living in metro Washington, DC, is not being able to consistently get really good farm fresh produce. It's fairly easy to get decent cucumbers, sweet corn is iffy, and tomatoes and stone fruits? Yeah, no.
Anyway, when it gets really hot and humid, do you make any changes to your diet to deal with it?