December in Charleston averages a daily high of 16.4°C with nights around 8.5°C. Expect roughly 8.4 wet days totalling 76.2mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Charleston is March–May.
Based on DOWNTOWN CHARLESTON, SC US (0.8km), 1995–2024. 30 years of December data.