December in Waltham averages a daily high of 5.3°C with nights around -4.6°C. Expect roughly 11.3 wet days totalling 101.2mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Waltham is May–June.
Based on BEDFORD HANSCOM FIELD, MA US (11.3km), 1995–2024. 27 years of December data.