December in Corvallis averages a daily high of 8.3°C with nights around 1.2°C. Expect roughly 22.1 wet days totalling 200.8mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Corvallis is June–September.
Based on CORVALLIS STATE UNIVERSITY, OR US (9.6km), 1995–2024. 30 years of December data.