September in Corvallis averages a daily high of 25.3°C with nights around 9.1°C. Expect roughly 7.3 wet days totalling 42.3mm. Comfortable conditions for being outdoors all day.
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 September data.