Sometimes it's just too hot to be outside and on those days we're OK just sticking indoors. But if you don't want to run your A/C constantly, let alone die of boredom, consider some alternative ways of keeping your dog cool. There are a wide variety of products and services that will help you do so and will also help you avoid standing out in the sun in the process. All you need is a bit of extra cash, since it's cheap to moderate in terms of price depending on what you get, plus a leash to walk them around and dog bags for picking up after your pal. The best part is, once you've come up with a solution for one hot day, you may have future hot days solved as well, leaving you to spend money only once to stay cool any number of blistering days.
While the regular lowlands may be battered with sun, often times higher elevations and shade can subtract double digit degrees off the thermometer. If there are good mountainous hiking spots nearby, consider taking a trip and finding out in person if they're able to provide a break from the heat. If nothing else, you'll have A/C on the ride there and back and will have future reference if your nearby location turns out.
If your dog has a longer coat that needs to be trimmed or maintained (or can even just be cut short and grown back), consider getting them fully groomed and trimmed so they have less hair to fight on hot days.