Why Do Iguanas Fall From Trees? Cold-Stunned in Florida

What happens to an iguana in the cold?

The green iguana is ectothermic, often called cold-blooded. It cannot produce enough body heat to stay warm on its own, so its body temperature follows its surroundings. Iguanas warm up by basking in the sun and cool down in the shade or in water. For more on how this works in all reptiles, see Are reptiles cold-blooded?.

In their native tropical forests from Mexico to South America, nights rarely get cold enough to matter. Green iguanas do best when their surroundings stay at roughly 26–35 °C (79–95 °F). When the air cools far below that, every process in the body slows down: muscles contract weakly, nerves send signals more slowly and digestion almost stops.

According to the Florida Fish and Wildlife Conservation Commission (FWC), green iguanas become sluggish once temperatures fall below about 10 °C (50 °F). If the air drops into the 4–7 °C (40–45 °F) range, they may become completely immobile. This state is called cold-stunning, a kind of temporary torpor.

The first warning sign is often color. On cool mornings green iguanas turn noticeably darker, which helps them soak up more heat from the sun, and they move slowly and stay close to their perches. On a truly cold night there is no sun to bask in, so they have no way of warming up until morning.

Why do they fall instead of climbing down?

Green iguanas spend the night high in trees, often on branches over canals or water where they are safe from predators. They usually settle in before temperatures drop. On a cold night the temperature falls while they are asleep, and by the time it is dangerously low they are already too slow to climb down.

As their muscles stiffen, they simply lose their grip and drop to the ground. Because they are motionless and stiff, they can look dead, which is why Florida news reports sometimes speak of “frozen iguanas” or “iguana showers.” In reality, they are chilled, not frozen.

Green iguanas are built to survive falls. In the wild they can drop up to about 15 m (50 ft) without injury, which is one reason so many survive these cold-weather tumbles.

Do cold-stunned iguanas survive?

Most do. As the morning sun warms them, their body temperature rises, their muscles start working again and they crawl away, often within hours. Many people have been surprised to see a “dead” iguana on the lawn suddenly come back to life.

Survival depends on how cold it gets and for how long. A single chilly night is usually survivable, but a long cold spell, several freezing nights in a row or temperatures near freezing can kill large numbers. Small iguanas cool faster than big ones because they have less body mass to hold heat, while very large adults can be slow to warm up again.

When does it happen in Florida?

Falling iguanas are a South Florida phenomenon. Green iguanas are an introduced species there (see Are iguanas invasive in Florida?), and most of the state’s iguanas live in the Miami area, Palm Beach County and the Florida Keys, where winters are usually mild.

Notable cold snaps that left iguanas dropping from trees include:

Cold weather events like these happen every few years, typically between December and February, and they hit iguanas again in early 2026.

Does the cold help control iguanas?

Cold snaps can reduce iguana numbers temporarily, and the severe January 2010 freeze killed many. But the population always recovered. Green iguanas breed quickly, with females laying clutches of a few dozen eggs every year, so a few mild winters are enough to rebuild their numbers.

The cold also limits where they can live. Regular frosts north of South Florida are the main reason green iguanas have not spread through the rest of the state or into neighboring states.

Do other animals do this?

Other tropical reptiles in Florida, including Burmese pythons and sea turtles, are also hit by cold. Sea turtles in cold water become “cold-stunned” in a similar way and float helplessly at the surface, and wildlife agencies rescue thousands in some winters. Native Florida reptiles such as alligators and many turtles handle cold better, often by sheltering in water or burrows where the temperature is more stable.