December in Newmarket averages a daily high of 0.8°C with nights around -6.2°C. Expect roughly 11.9 wet days totalling 54.9mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Newmarket is May–September.
Based on BALDWIN, ON CA (26.9km), 1995–2024. 18 years of December data.