We've since set up a sprinkler on part of their yard, to keep them cooler and provide a continuous fresh water supply all day. So far, so good.
The good news (depending on how you feel about kittens) is that the calico cat that showed up a couple of months ago, has four kittens. She kept them hidden for at least three weeks and just brought them for a visit last week. It's hard not to smile when kittens tumble over each other or pounce on their mother's tail as she tries to eat.
Aren't they adorable?