Whatever type of clay/dirt our house is built on tends to contract a lot when it gets dry. So much that the foundation shifts, and if not watered could result in expensive damage. So saith various inspectors and contractors. So we (along with a lot of our neighbors) routinely water the area around the house during the summer. I can actually tell the difference via the closet door I mentioned.
This plagued my parents (similar soil, different state) so much that they installed a buried foundation watering system on timers.