Winters stretch from mid-November to mid-March and temperatures can fall dramatically with occasional snowfall. Average daily temperatures are around 6 or 7°C. Rainfall during the winter is no greater than during the rest of the year although there can be freak rainstorms so it is advisable to take both warm and waterproof clothing if visiting the city during the winter months.
For daily weather information on Atlanta you should look at the
weather page which i think you will find useful.