September in Union averages a daily high of 25.7°C with nights around 16.3°C. Expect roughly 8.6 wet days totalling 104.6mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Union is May–June.
Based on NEWARK LIBERTY INTERNATIONAL AIRPORT, NJ US (8.1km), 1995–2024. 30 years of September data.