Well...not quite. 

The recent cold snap we had down here dipped temperatures down into the high 30's (even colder with the wind chill).  When the temperature drops into the 40's, cold-blooded reptiles fall into a deep sleep.  Kind of a suspended animation state.  Since iguanas love to hang out in trees...you can imagine what happens when the cold sleep sets in.  You got it...they fall right off the tree.  I can only imagine the site...plop...plop...  Don't worry though...once the temperatures rise, they snap out of the sleepy state and are back to normal (but if it's too cold...for too long, it can kill these guys).  Many of Floridians wouldn't be too sad to see them killed off though...they've become an invasive species.

South Florida has quite a few iguanas running around even though they are not native to the area.  They were brought into the area as pets and when they grow too large or when people just get tired of them...they let them go.  It's actually become a problem in some areas of Florida since they thrive in our climate and have no real natural predators and they reproduce fairly quickly.  They even snack on native small animals and bird eggs.  They can grow to be about 6 feet long...but most you see around aren't that large. 

You can usually find them along canals...sometimes sunning on the grassy banks or hanging out in a tree.