September in Harrisburg averages a daily high of 24.5°C with nights around 13.2°C. Expect roughly 9.2 wet days totalling 126.9mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Harrisburg is May–June.
Based on HARRISBURG 1 NE, PA US (1.5km), 1995–2024. 27 years of September data.