December in Ueda averages a daily high of 5.5°C. Expect roughly 6.1 wet days totalling 35.7mm. Demanding conditions — pack for it and plan indoor options.
Across the year, the best time to visit Ueda is May–September.
Based on KARUIZAWA, JA (24.7km), 1995–2024. 27 years of December data.