September in Iwamizawa averages a daily high of 22.8°C. Expect roughly 10.7 wet days totalling 136mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Iwamizawa is June–September.
Based on IWAMIZAWA, JA (2.6km), 1995–2024. 26 years of September data.