I have to agree with Willowy, with the unless they are trapped in sun or an enclosed area. They know not to stay in the sun. I too worry with Zoe over heating, but she's smart. I check on her a LOT during the day, 99% of the time she's under the porch, and will only be in direct sunlight for a few minutes while she's watching something. I try to get her to come in, and yeah...she'd rather be out playing! She'll come in for an afternoon nap and then time to go! Just make sure the kitties stay hydrated. Even though Zoe prefers her drinks from the sink, I still make sure there is a water bowl outside.