In Atlanta, where temperatures are set to drop below freezing early Monday morning, forecasters warn of even colder air by late in the week, according to the National Weather Service office in Peachtree City, Georgia.The low Friday night in Atlanta will be around 13 degrees (minus 10.6 Celsius) with the high temperature Saturday still below the freezing mark at around 29 degrees (minus 1.7 Celsius), the Weather Service projects.Freezing temperatures can take lives in an instant — a heartbreaking reality that Atlanta homeless advocate George Chidi knows firsthand.Homeless people in southern states are also vulnerable to its weather patterns that make it comfortable one week, but suddenly freezing the next.Northern Florida cities such as Jacksonville, Tallahassee and Pensacola have predicted lows in the 20s (minus 3 Celsius) on Christmas Eve, with highs of about 40 (4 Celsius)."