December in Sankt Gallen averages a daily high of -3.1°C with nights around -8.3°C. Expect roughly 16.5 wet days totalling 289mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Sankt Gallen is June–August.
Based on SAENTIS, SZ (19.4km), 1995–2024. 29 years of December data.