May in Bismarck averages a daily high of 20.1°C with nights around 5.8°C. Expect roughly 10.8 wet days totalling 64.5mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Bismarck is May.
Based on BISMARCK MUNICIPAL AIRPORT, ND US (4.5km), 1995–2024. 30 years of May data.