September in Sơn La averages a daily high of 29.6°C. Expect roughly 11.3 wet days totalling 108.5mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Sơn La is October–March.
Based on SON LA, VM (2.1km), 1995–2024. 17 years of September data.