December in Rock Hill averages a daily high of 13.2°C with nights around 2.1°C. Expect roughly 9.1 wet days totalling 96.5mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Rock Hill is April–May.
Based on WINTHROP UNIVERSITY, SC US (1.8km), 1995–2024. 25 years of December data.