August in Waltham averages a daily high of 28.1°C with nights around 15.5°C. Expect roughly 12.1 wet days totalling 92.8mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Waltham is May–June.
Based on BEDFORD HANSCOM FIELD, MA US (11.3km), 1995–2024. 26 years of August data.