May in Gießen averages a daily high of 19.4°C with nights around 7.9°C. Expect roughly 11.6 wet days totalling 64mm. 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. 30 years of May data.