Not sure I would keep them out in the open outside. Every month or so I have a rat that gets out of the tub and runs around the room, usually when I'm cleaning the racks, it just happens. If it got away from you outside I'm guessing it would be nearly impossible to catch it and you would start your own rat infestation in the neighborhood LOL. It's probably best to keep them in a small shed, run an extension cord out there and maybe run a swamp cooler / evaporative cooler on some kind of thermostat. I'd also run a heater on a thermostat so it doesn't get too cold. I keep my rats in my snake room at a constant 81F, I wouldn't go much higher than that.