May in Bolu averages a daily high of 22°C with nights around 8.1°C. Expect roughly 13.8 wet days totalling 67.5mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Bolu is June–October.
Based on BOLU, TU (0.6km), 1995–2024. 26 years of May data.