September in Sankt Gallen averages a daily high of 6.4°C with nights around 1.5°C. Expect roughly 14.9 wet days totalling 214.3mm. 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. 30 years of September data.