December in Ōshū averages a daily high of 7.5°C. Expect roughly 9.2 wet days totalling 78.4mm. Demanding conditions — pack for it and plan indoor options.
Across the year, the best time to visit Ōshū is May–June.
Based on OFUNATO, JA (48km), 1995–2024. 26 years of December data.