June in Kostroma averages a daily high of 21.8°C with nights around 11.1°C. Expect roughly 13 wet days totalling 75.9mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Kostroma is May–August.
Based on KOSTROMA, RS (5.9km), 1995–2024. 25 years of June data.