September in Gresham averages a daily high of 24.6°C with nights around 11.2°C. Expect roughly 6.9 wet days totalling 45.8mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Gresham is June–September.
Based on PORTLAND TROUTDALE AIRPORT, OR US (6.1km), 1995–2024. 27 years of September data.