National Weather Service forecasters issued the warning Tuesday morning. They say the storm could reach "historical proportions."
Many residents already are heeding officials' advice to stay home. Schools are canceled, and Atlanta streets were largely empty during the usually busy morning commute.
Forecasters say widespread outages are possible as ice builds up on trees and power lines. The ice threat is expected to begin in Georgia overnight. As much as 9 inches of snow could fall in parts of north Georgia by Wednesday night.
Other areas of the South, from the Carolinas to Alabama, also were expected to see a wintry mix of snow, ice and freezing rain.