Frozen washcloths & some 'cool' meals ideas...
I wet washcloths and store them inside a container in the freezer separated by freezer paper, pull them out to cool your face but especially the back of your neck, it really helps with people prone to heatstroke. It works for pets too, to give them a bit of a break, and because the cloths immediately go in the laundry - when the weather's hot you really need to have a big supply on hand in the freezer.
For meals, I grill chicken breasts and make a batch of couscous or quinoa (which is high in protein), they hold in the fridge pretty well for several days so the options for chicken salads, sandwiches, in tortillas, etc are pretty endless. It's so easy to mix them with a sauce or two and have a great tasting meal. Another hot weather favorite is having a fruit smoothie as a meal replacement, with protein powder or soft tofu mixed in, it makes a good meal replacement. It doesn't have to be an elaborate smoothie: even frozen fruit blended with water works just fine (I use fruit juice or concentrate as the sweetener). Gazpacho is great, in all its many variations, for hot weather. Overall I find that the fewer temperature fluctuations I experience (including with hot or cold food or in/out of air conditioning) the easier it is to survive the heat.
For drinks... homemade lemonade with lemonade ice cubes (so it doesn't become watery) and a mint iced tea are favorites (right now, it's simply spearmint tea, brewed, then iced and it's really refreshing). And regular water ice cubes for the pets drinking bowls. In this last heat wave even the cats were panting but they sure seemed to like the iced water (at least they chased the cubes around their water bowl!).