Boston in September
In September, Boston averages 23°C (73°F) during the day and 13°C (55°F) at night, with around 9 days of rain (85 mm total).
ShoulderConditions are comfortable for sightseeing without being sweltering. Occasional showers are likely but won't dominate.
It's peak hurricane season in Boston during September. Travel is possible but expect storm risk, possible flight disruption, and generally lower travel insurance coverage.
How September compares to the rest of the year in Boston
September is in the middle of the year for warmth in Boston (4th of 12) and one of the driest months (12th of 12). Daytime temperature runs 8°C above the annual average (15°C). September runs 4°C cooler than August (27°C) and cools 6°C in October (17°C).
September sunrise & sunset in Boston
Times shown for Boston local time (America/New_York), calculated for the 15th of September. They shift by a few minutes day to day across the month.
Photography light in Boston — September
Golden-hour and blue-hour windows for the 15th of September, in Boston's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Boston in September
Travel writers usually only tell you when to go. Here's when to book flights and lodging for the best mix of price and availability, based on September's tier (Shoulder) and Boston's popularity.
Crowds & pricing — September in Boston
Boston is in a shoulder season month — fewer crowds, slightly lower prices, and a calmer atmosphere than peak weeks. Most major sights stay open with normal hours, though a handful of seasonal restaurants or boat trips may run reduced schedules. Many regulars consider these months the best time to visit because you trade a small amount of weather reliability for a much more pleasant on-the-ground experience.
Why this tier: excellent tourism weather peak hazard season (1 active)
Sun & mosquito risk — September in Boston
UV is a clear-sky sea-level estimate — clouds, altitude, and reflective surfaces (snow, water) shift it ±30%. Mosquito risk is climate-derived only; for current disease advisories (dengue, malaria, zika) check the CDC or WHO travel pages before your trip.
Sea temperature in Boston — September
Across the year Boston's sea swings from 3.5°C (February) to 19.6°C (August) — September sits at 19.4°C.
Boston in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 2°C / 36°F | -6°C / 21°F | 88 mm | 10 | 10 |
| February | 3°C / 37°F | -5°C / 23°F | 88 mm | 10 | 9 |
| March | 7°C / 45°F | -1°C / 30°F | 104 mm | 11 | 5 |
| April | 14°C / 57°F | 4°C / 39°F | 92 mm | 11 | 1 |
| May | 19°C / 66°F | 9°C / 48°F | 88 mm | 11 | 0 |
| June | 25°C / 77°F | 15°C / 59°F | 95 mm | 11 | 0 |
| July | 28°C / 82°F | 18°C / 64°F | 84 mm | 9 | 0 |
| August | 27°C / 81°F | 17°C / 63°F | 94 mm | 9 | 0 |
| September | 23°C / 73°F | 13°C / 55°F | 85 mm | 9 | 0 |
| October | 17°C / 63°F | 7°C / 45°F | 96 mm | 10 | 0 |
| November | 11°C / 52°F | 2°C / 36°F | 108 mm | 11 | 1 |
| December | 5°C / 41°F | -3°C / 27°F | 106 mm | 12 | 7 |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for Boston in September →
Frequently asked questions
How hot is Boston in September?
In September, Boston averages a high of 23°C (73°F) and a low of 13°C (55°F) — generally mild and pleasant.
Does it rain a lot in Boston in September?
September sees occasional rain in Boston, with about 9 rainy days on average.
Is September a good time to visit Boston?
September is mild and pleasant. It suits travelers who are comfortable with mild and pleasant weather; check the month-by-month ranking to compare it against the rest of the year.
What should I pack for Boston in September?
Pack light layers for warm days and cooler evenings. See the full September packing list for Boston for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.