December in Ansan-si averages a daily high of 4.2°C with nights around -2.5°C. Expect roughly 3 wet days totalling 14mm. Demanding conditions — pack for it and plan indoor options.
Across the year, the best time to visit Ansan-si is May–June.
Based on INCHEON, KS (23.1km), 1995–2024. 17 years of December data.