September in Barrie averages a daily high of 21.5°C with nights around 10.7°C. Expect roughly 10.5 wet days totalling 77.9mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Barrie is May–September.
Based on SHANTY BAY, ON CA (2.6km), 1995–2024. 29 years of September data.