Boston Weather in September
United States · Humid Continental climate · Data averaged from 2020-01-01 to 2024-12-31 (5 years)
September in Boston sees average temperatures ranging from a low of 14.5°C (58.1°F) to a high of 23.0°C (73.4°F), with a mean of 18.5°C (65.3°F). Compared to the annual average of 11.2°C (52.2°F), this month is 7.3°C warmer than the yearly norm. Precipitation averages 126.5mm, making it approximately 25.0mm wetter than the monthly average of 102.0mm. The city receives an average of 8.9 hours of sunshine per day during September, with relative humidity averaging 76.2%. Wind speeds reach an average maximum of 18.4 km/h. For travelers, this month offers a temperature experience in Boston, with wetter-than-average conditions compared to the rest of the year.
Boston's four distinct seasons make it one of the most dynamic New England cities for climate study. I've tracked the data and found that the city experiences beautiful autumns, cold winters, mild springs, and warm summers. The best time for visiting is May to October, with September being the ideal month for comfortable temperatures and the famous fall foliage.
September vs Adjacent Months
| Metric | August | September | October |
|---|---|---|---|
| Mean Temp | 22.7°C (72.9°F) | 18.5°C (65.3°F) | 13.1°C (55.6°F) |
| Rainfall | 92.2mm | 126.5mm | 116.1mm |
| Sunshine | 10.7 hrs | 8.9 hrs | 7.8 hrs |
| Humidity | 73.6% | 76.2% | 76.7% |
| Wind | 18.4 km/h | 18.4 km/h | 18.6 km/h |
| Rainy Days | 17.0 | 14.8 | 11.2 |
| Snowfall | 0.0 cm | 0.0 cm | 1.7 cm |
Seasonal Context
September falls in Autumn in the Northern Hemisphere. Autumn sees temperatures gradually cooling from summer highs. For travelers visiting Boston in September, the data indicates mixed conditions based on the combination of temperature, precipitation, and daylight hours.
Frequently Asked Questions
What is the average temperature in Boston in September?
The average temperature in Boston during September ranges from 14.5°C (58.1°F) to 23.0°C (73.4°F), with a mean of 18.5°C (65.3°F).
How much does it rain in Boston in September?
Boston receives an average of 126.5mm of precipitation in September, spread across approximately 14.8 rainy days.
What should I pack for Boston in September?
Based on September weather data, pack layers including light jackets and t-shirts, plus an umbrella. Rain gear is essential — this month averages 126.5mm of precipitation.
Is September a good time to visit Boston?
September is a month with challenging conditions. Plan activities carefully and stay hydrated.
Other Months for Boston
Cities with Similar September Climate (Humid Continental)
Data Source: Open-Meteo historical archive (2020-01-01 to 2024-12-31). Daily measurements aggregated into monthly climate normals. Coordinates: 42.36°, -71.06°. Timezone: America/New_York. Last updated: 2026-07-30.