September in Trier averages a daily high of 20.7°C with nights around 10.1°C. Expect roughly 10.1 wet days totalling 59.6mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Trier is May–September.
Based on TRIER PETRISBERG, GM (1.6km), 1995–2024. 30 years of September data.