Boston, Massachusetts weather in May

Averages from 2021–2025 (155 days of record).

Average high: 68°F
Average low: 50°F
Rainy days: ~11 per month
Total precipitation: 4.4 in
Warmest recorded: 93°F
Coldest recorded: 37°F

Expect May days in Boston, Massachusetts to top out around 68°F and cool to about 50°F overnight, with roughly 11 days of measurable rain across the month. In recent years May has ranged from 37°F to 93°F.

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Current Boston, Massachusetts forecast → · Historical data by Open-Meteo (ERA5).