May in Boston averages a daily high of 19.3°C with nights around 10.3°C. Expect roughly 11.9 wet days totalling 86.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Boston is May–September.
Based on BOSTON LOGAN INTERNATIONAL AIRPORT, MA US (4.1km), 1995–2024. 30 years of May data.