January in Irkutsk averages a daily high of -13.1°C with nights around -21.8°C. Expect roughly 11.4 wet days totalling 16.2mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Irkutsk is May–August.
Based on IRKUTSK, RS (5.2km), 1995–2024. 25 years of January data.