January in Jena averages a daily high of 4.5°C with nights around -1.2°C. Expect roughly 14.4 wet days totalling 36.6mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Jena is May–September.
Based on JENA STERNWARTE, GM (0.5km), 1995–2024. 30 years of January data.