September in Mount Vernon averages a daily high of 25.2°C with nights around 18°C. Expect roughly 8.1 wet days totalling 110.3mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Mount Vernon is May–June.
Based on LAGUARDIA AIRPORT, NY US (15.3km), 1995–2024. 30 years of September data.