September in Gießen averages a daily high of 20°C with nights around 9.3°C. Expect roughly 10.3 wet days totalling 48.5mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Gießen is May–September.
Based on GIESSEN WETTENBERG, GM (2.3km), 1995–2024. 29 years of September data.