May in Nampa averages a daily high of 22.2°C with nights around 8.4°C. Expect roughly 8.7 wet days totalling 39mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Nampa is June.
Based on BOISE AIR TERMINAL, ID US (26.2km), 1995–2024. 30 years of May data.