May in Białystok averages a daily high of 19.3°C with nights around 7.8°C. Expect roughly 12.8 wet days totalling 70.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Białystok is May–September.
Based on BIALYSTOK, PL (3.7km), 1995–2024. 30 years of May data.