September in Viersen averages a daily high of 20.8°C with nights around 10.7°C. Expect roughly 12.3 wet days totalling 59.9mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Viersen is May–September.
Based on TONISVORST, GM (5.4km), 1995–2024. 30 years of September data.