September in Sanjō averages a daily high of 26.6°C. Expect roughly 12.8 wet days totalling 154.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Sanjō is May–June.
Based on NIIGATA, JA (34.5km), 1995–2024. 20 years of September data.