I have my adult male Russian outside to wander around his tortoise garden, but the humidity is high today. The high today is 85°F (29°C), the humidity is currently at 65%, the dew point is at 72°F (22°C), and the heat index is 90°F (32°C). How long should he be outside for at the maximum? (We have the AC on inside.) I don't want him to get too stressed out! Thanks!