December in Idaho Falls averages a daily high of 0°C with nights around -8.5°C. Expect roughly 10.3 wet days totalling 28.8mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Idaho Falls is June.
Based on IDAHO FALLS KIFI, ID US (5.5km), 1995–2024. 27 years of December data.