December in Ishim averages a daily high of -9.9°C with nights around -18.2°C. Expect roughly 13.3 wet days totalling 24.9mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Ishim is May–August.
Based on ISCHIM AMSG, RS (3.8km), 1995–2024. 24 years of December data.