December in Nampa averages a daily high of 3.9°C with nights around -3.5°C. Expect roughly 12.6 wet days totalling 42.2mm. A hard month to visit for comfort alone.
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 December data.