We moved a few months ago, from the SW corner of Oklahoma. Woo-baby was it ever hot there! In fact, I see on FB that this weekend my friends who remain there might see temps up to 111 degrees. Yikes.
If it's hot where you live, try this idea: a bucket of good old H20 and some paint brushes (like the kind you use to paint walls -- buy the cheap ones at Wal-Mart or the Dollar Store if you don't have any lying around in your garage) and head out to the driveway. On the right kind of day, your kids can paint to their hearts content, and the "paint" will dry within a few seconds.
We have also painted the brick of our house and the garage door, but you might not want to set this precedent. You know -- in case your little Picasso ever gets his or her hands on some actual paint.
I know you're thinking this sounds too easy to work, but I'm telling you, it does. Happy painting!