December in Kennewick averages a daily high of 5.2°C with nights around -1.2°C. Expect roughly 11.2 wet days totalling 31mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Kennewick is May–June.
Based on KENNEWICK, WA US (2.8km), 1995–2024. 30 years of December data.