Temperatures are dropping so low in South Florida that stunned iguanas are starting to fall from the treetops.

Footage from Dania Beach, Florida shows a number of the reptiles lying flat on their backs on the floor having fallen from the treetops.

Low temperatures stun the scaly creatures - dislodging them from their leafy perch and causing them to drop to the ground.

The lizards are cold blooded, meaning their muscle activity depends on chemical reactions which run quickly when it is hot and slowly when it is cold.

The recent cold weather has left them sluggish and immobile, causing them to fall from trees.

On Wednesday forecasters issued a warning to residents about falling iguanas.

"This isn't something we usually forecast, but don't be surprised if you see Iguanas falling from the trees tonight as lows drop into the 30s and 40s. Brrrr!" NWS Miami tweeted.

Though stunned, the invasive reptiles won't necessarily die and are likely to wake up again once temperatures rise.

Stunned iguanas cling to tree roots after falling into waters following chilly temperatures. Credit: AP

Iguanas aren't dangerous or aggressive to humans, but they damage seawalls, sidewalks, landscape foliage and can dig lengthy tunnels.

The males can grow to at least 5 feet (1.5 meters) long and weigh nearly 20 pounds (9 kilograms).

Female iguanas can lay nearly 80 eggs a year, and South Florida's warm climate is perfect for the prehistoric-looking animals.

One iguana hangs around waiting for sunrise before moving on for the day. Credit: AP

Iguanas are native to Central America, tropical parts of South America and some Caribbean islands.

Iguanas are allowed to be kept as pets in Florida but are not protected by any law except anti-cruelty to animals.

They've been in South Florida since the 1960s, but their numbers have increased dramatically in recent years.