Iguanas cannot stand cold weather because they have cold blood when the temperature drops below about 45 degrees their bodies become inactive. They look dead, but they are not. They continue to breathe with critical body functions still operational.
This phenomenon, mixed with the tendency of the species to sleep in trees, can create a surprise for someone who goes in a car or walks under a tree, and since some iguanas are large: adult males can weigh the 5 meters long up to 20 pounds: can be dangerous for passers-by.
The danger of the iguana comes when temperatures remain in the 1940s for periods of more than eight hours. Invasive species are at risk of death, especially the smaller ones.
“The temperature threshold for when iguanas begin to go dormant depends largely on the size of the iguana,” Ron Magill, director of communications at Miami Zoo told CNN when temperatures dropped in January. “In general terms, the bigger the iguana, the colder it can tolerate for longer periods.”
He also commented that many South Florida iguanas have adapted to dig deep burrows, so they are isolated from the cold. Iguanas also tend to live near large bodies of water, which can be warmer than air temperatures, so it can help them survive short periods of cold.