December in Saint John averages a daily high of 3°C with nights around -5°C. Expect roughly 13.1 wet days totalling 109.2mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Saint John is July–September.
Based on POINT LEPREAU CS, NB CA (38.3km), 1995–2024. 26 years of December data.