I live in Ohio, and have owned iguanas off and on for years, but I'm not an "expert". But I can tell you that I haven't had any issues with my iguana during the cold season. Just make sure the cage/tank is not near a window or outside facing wall that can get cold during the winter. I can also tell you to make sure you follow the food chart on this site! When I was younger I fed my iguanas broccoli, carrots, and cauliflower since that was cheap and I could find it at every grocery store nearby. I thought that was a good diet for an herbivore. Turns out I was wrong, and with my son's iguana we've been basing her diet off the food chart - what a difference!