While it is Raining Iguanas, Chameleons Survive

Cold Resistance in Florida's Invasive Lizards: Iguana iguana vs. Chamaeleo calyptratus

The Green Iguana (Iguana iguana) thrives only in tropical climates, where daytime temperatures average 27–32 °C (80–90 °F) and nights remain above 21 °C (70 °F). In South Florida, when winter temperatures dip into the low 40s °F (~5 °C), iguanas become immobilized, often falling from trees in dramatic scenes. Prolonged exposure to the 30s °F (~0–4 °C) is fatal, as their native range never subjects them to such cold, and evolution has not equipped them with survival mechanisms.

By contrast, the Veiled Chameleon (Chamaeleo calyptratus) originates from Yemen's highlands, between 4000 ft (≈1200 m) and over 8200 ft (≈2500 m) above sea level. Here, summers are mild, averaging 27 °C by day and 18 °C at night, while winters regularly drop below 20 °C in daylight and under 10 °C at night, with occasional dips to freezing. This species has evolved strategies to endure cold: descending to the ground, seeking shelter in dense vegetation, moss or leaf litter, and even burrowing into soil. Their genetic memory of these conditions allows them to survive Florida's winter lows far better than iguanas, making C. calyptratus notably more cold‑resistant.