January in Yachimata averages a daily high of 10.2°C. Expect roughly 5.4 wet days totalling 50.5mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Yachimata is April–June.
Based on CHIBA, JA (20.4km), 1995–2024. 26 years of January data.