Boston, Massachusetts weather in August

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

Average high: 81°F
Average low: 64°F
Rainy days: ~12 per month
Total precipitation: 3.5 in
Warmest recorded: 100°F
Coldest recorded: 54°F

Expect August days in Boston, Massachusetts to top out around 81°F and cool to about 64°F overnight, with roughly 12 days of measurable rain across the month. In recent years August has ranged from 54°F to 100°F.

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