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Boston in September: weather, sea & travel advice
This month's data profile
Strong month under the current formula
Boston in September is climatically well suited to city breaks, active holidays and hiking and family holidays. The average daily high is around 23 °C, and the sea is about 17 °C. With about 10 rainy days it is wet.
Historical monthly averages, not a weather forecast. Individual days and years can differ substantially.
Rank among 12 monthly averages
72/100 · #1
Warmth
#4
Dryness
#4
Sun
#6
Sea warmth
#3
Published best categories: Overall, Beach, City break, Active, Family
Boston · SeptemberPhoto: Chris Wood ( User:chris_j_wood ) · CC BY-SA 4.0Climate facts
- Average high
- 23 °C
- Average low
- 13 °C
- Sea
- 17 °C
- Rainy days (est.)
- 10 rainy days (est.)
- Sun (est.)
- 5 h/day
- Humidity
- 75 %
Climate evidence with direct month comparison
The highlighted row is the selected month. Precipitation total and rainy days are separate monthly averages.
| Month | Avg high °C | Avg low °C | Rainy days (est.) | Precipitation mm | Sun h/day (est.) | Humidity % | Wind m/s | Sea °C | Score |
|---|---|---|---|---|---|---|---|---|---|
| August | 27 | 17 | 12 | 92 | 6.6 | 73 | 0.4 | 19 | 70 |
| September (selected) | 23 | 13 | 10 | 104 | 5.2 | 75 | 0.5 | 17 | 72 |
| October | 17 | 7 | 10 | 116 | 3.6 | 78 | 0.6 | 14 | 49 |
How do the previous and next months compare?
Baseline: September (72/100)
Positive and negative values show the change from the selected month.
| Score Δ | Average high Δ | Average low Δ | Rainy days Δ | Rain Δ | Sun Δ | Humidity Δ | Wind Δ | Sea Δ | |
|---|---|---|---|---|---|---|---|---|---|
| August | -2 | +3.9 °C | +3.9 °C | +1.6 | -11.3 mm | +1.4 h | -2 % | -0.1 m/s | +1.6 °C |
| October | -23 | -6.9 °C | -5.9 °C | -0.1 | +12.4 mm | -1.6 h | +3.3 % | +0.1 m/s | -3.5 °C |
All twelve months in context
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Useful next decisions
Frequently asked questions
How warm is Boston in September?
The average daily high is around 23 °C, with an average daily low of about 13 °C.
Can you swim in Boston in September?
The sea is about 17 °C (cold).
Does it rain a lot in Boston in September?
The curated estimate is about 10 rainy days per month, not a directly measured long-term average. Total precipitation averages around 104 mm for the month. A rainy day does not mean all-day rain.
When is the best time to visit Boston?
By the climate score, June, July, August and September are the strongest months for Boston. For a beach trip: July, August and September. September is one of them.