December in Lethbridge averages a daily high of 0.3°C with nights around -10.8°C. Expect roughly 4.3 wet days totalling 6.4mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Lethbridge is July–September.
Based on LETHBRIDGE CDA, AB CA (3.7km), 1995–2024. 27 years of December data.