September in Knoxville averages a daily high of 28.3°C with nights around 15.5°C. Expect roughly 7.8 wet days totalling 105.3mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Knoxville is April–May.
Based on KNOXVILLE EXPERIMENTAL STATION, TN US (7.7km), 1995–2024. 28 years of September data.