July in Waltham averages a daily high of 29°C with nights around 16.6°C. Expect roughly 12.5 wet days totalling 97.8mm. 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. 25 years of July data.