September in Barnaul averages a daily high of 18°C with nights around 5.7°C. Expect roughly 10.4 wet days totalling 31.6mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Barnaul is May–September.
Based on BARNAUL, RS (16.1km), 1995–2024. 27 years of September data.