August in Somerville averages a daily high of 27.1°C with nights around 18.7°C. Expect roughly 9.3 wet days totalling 80.5mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Somerville is May–September.
Based on BOSTON LOGAN INTERNATIONAL AIRPORT, MA US (8km), 1995–2024. 30 years of August data.