September in Kouvola averages a daily high of 15.3°C with nights around 7.3°C. Expect roughly 11.7 wet days totalling 59.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Kouvola is May–August.
Based on KOUVOLA UTTI LENTOPORTINTIE, FI (13.5km), 1995–2024. 30 years of September data.