I waited until it was at least 65 and sunny or partly cloudy. We have a dry heat here in my part of Colorado so I didn't have him out longer than 30min. He was very skiddish because of all the birds so he was actually very keen on staying on me lol. My take is alot like Bemans if you're too hot in direct sunshine in warm weather clothing then more than likely so would your cham. Shade is key on hotter days!