MIAMI - It's a South Florida phenomenon that draws amusement from across the country — when temperatures drop below a certain level, cold-stunned iguanas start falling out of trees. While it may sound bizarre, it happens. And there's a scientific reason for it.

The first of several cold fronts expected to hit Florida the first part of January is here. It was colder early Friday morning in Tallahassee than it was was across several portions of the North and West. Think Washington, Idaho, Wyoming and Utah.

Frigid temperatures have been infiltrating the U.S. over the past several days, and Florida hasn’t been immune to the bitter blast of cold air.

Snow, ice, strong winds and plunging temperatures in the US have led to dangerous travel conditions from central and southern states.