August in Nagaoka averages a daily high of 30.7°C. Expect roughly 10.4 wet days totalling 139.2mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Nagaoka is May–June.
Based on NIIGATA, JA (54.8km), 1995–2024. 20 years of August data.