September in Halton Hills averages a daily high of 22.9°C with nights around 9°C. Expect roughly 9.9 wet days totalling 69.3mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Halton Hills is May–September.
Based on GEORGETOWN WWTP, ON CA (4km), 1995–2024. 21 years of September data.