Last updated: February 24, 2025
Experience the vibrant weather of September in Boston, where the temperature ranges from a chilly 7°C (46°F) to a warm 33°C (92°F), creating a pleasant average of 19°C (67°F). This month sees approximately 92 mm (3.6 in) of rainfall spread over 8 days, contributing to the city's humid atmosphere with a relative humidity of 71%. As summer transitions to fall, Boston showcases a dynamic climate that invites both locals and visitors to enjoy its diverse outdoor activities and stunning autumn foliage, making it a perfect time to explore the rich culture of this historic city.
In September, Boston welcomes the transition from summer's heat to fall's embrace with temperatures that offer a delightful mix. The month begins with a minimum temperature around 7°C (46°F), setting a crisp tone for early autumn. As days go by, the average temperature maintains a comfortable 19°C (67°F), perfect for outdoor activities and enjoying the vibrant foliage. The warmth of up to 33°C (92°F) can still linger, reminiscent of summer, but the cooler nights hint at the changing season. This blend of warmth and coolness creates an inviting atmosphere, making September in Boston a truly enchanting time to explore the city as it shifts gears into fall.
September in Boston typically sees a moderate precipitation amount of 92 mm (3.6 in), making it a relatively wet month compared to the summer but less so than the wetter autumn months ahead. With precipitation occurring over just 8 days, the rain tends to be spaced out, allowing for plenty of crisp, sunny days amid the showers. This pattern not only supports the transition from summer to fall but also marks the beginning of the city's vibrant autumn foliage, as cooler temperatures usher in a new season. Overall, September serves as a bridge between the lush vibrancy of summer and the rich, changing colors of fall, characterized by a balanced mix of rain and sun.
As summer gives way to fall, September in Boston brings a noticeable shift in humidity, averaging around 71%. This marks a slight uptick from the drier months of July and August, which recorded 67% and 66% respectively. Overall, September stands as a transitional period, showcasing more comfort than the oppressive humidity of the peak summer months. Following this month, humidity levels begin to rise again as the city prepares for autumn, peaking in October at 78% before settling back into the higher levels typical of the winter months. This pattern highlights the journey from the sultry heat of summer to the crispness of fall, offering a refreshing yet humid reprieve for Bostonians.
As summer wanes, September in Boston sees a notable shift in the UV Index, dipping to a level of 7, categorized as high. This marks a gradual decrease from the peak levels experienced during the sun-soaked months of June and July, where indices soared to 10 and 9, respectively. The burn time also reflects this transition, extending to 25 minutes, allowing for a bit more outdoor enjoyment compared to the intense sun of midsummer. As we move into the fall, the UV Index continues to decline, leading into October with a UV Index of 6. It's important to stay mindful of sun exposure during this time as the UV rays, although less intense, can still pose a risk. For more details on safe sun practices, check the comprehensive guide on the Boston UV Index.
UV Risk Categories
As September unfolds in Boston, the city basks in a glorious 278 hours of sunshine, marking a gentle decline from the sun-soaked days of summer. Following the peak of 334 hours in July, the warm glow lingers, allowing residents to relish crisp air and vibrant autumn foliage. This transition showcases the typical seasonal shift, as September maintains a robust level of sunshine compared to earlier months like April or May, which have 240 and 289 hours, respectively. With autumn’s arrival, the warm light gradually fades, paving the way for October’s cooler climate and a significant drop to 221 hours. However, September remains a cherished time for outdoor activities, striking the perfect balance between summer’s vibrancy and fall’s embrace.
In September, Boston enjoys a 44% chance of sunny weather, a figure mirroring the sun's elusive presence earlier in the year, with January and October also falling within the same range. This month often marks a transitional period as summer wanes, yet it maintains a relatively optimistic outlook for sunshine compared to the latter months. Notably, September's sun probability aligns closely with the winter months, suggesting a consistency in weather patterns as the city begins to shift into fall. As we move deeper into autumn, the likelihood of sunny days typically sees a gradual decline, with November boasting a surprising 55% chance that may offer a final burst of warmth before winter's chill sets in. This interplay of sun and seasonality makes September a delightful time in Boston, though one should always be prepared for the unpredictable New England weather.
As September rolls in, Boston bids farewell to the summer's generous 15 hours of daylight, gracefully transitioning into shorter days. This month enjoys a pleasant balance with 12 hours of daylight, marking a gradual decrease from the sun-soaked heights of June and July. The trend reveals a clear shift as the vibrant colors of autumn begin to appear, leading towards the shorter days of fall. With October looming, the daylight diminishes to 11 hours, reflecting the inevitable approach of winter. Thus, September serves as a beautiful bridge, encapsulating the lingering warmth of summer while hinting at the cozy, shorter days ahead.
September in Boston ushers in a subtle shift in the breeze, with average wind speeds settling at 3.7 m/s (8 mph). This slight increase from the languid months of July and August signals a refreshing change as summer transitions into autumn. Interestingly, while other months witness more robust winds, September's gentle gusts provide a serene backdrop for the city's vibrant foliage to start budding. The data reveals a trend of decreasing wind speeds during the summer, followed by a gradual uptick in the fall months, setting the stage for Boston's characteristic autumn charm. As the crisp air begins to envelop the city, the winds in September serve as a reminder of nature's cycles, blending the remnants of summer warmth with the impending coolness of the season.
The weather in Boston changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of September's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Boston and find detailed weather information for every month.
September and January present strikingly different weather patterns. In September, temperatures can range from a cool 7°C (46°F) at night to a warm 33°C (92°F) during the day, with an average of 19°C (67°F). The month experiences about 92 mm (3.6 in) of precipitation over approximately 8 days, accompanied by a humidity level of 71%. In contrast, January is characterized by much colder temperatures, with a minimum of -19°C (-3°F) and an average around 0°C (32°F), rising to a maximum of 19°C (67°F) on warmer days. This month sees slightly less precipitation at 79 mm (3.1 in) over 9 days, but the humidity is higher at 86%. For more details on January weather, check out Boston weather in January.
September and February present striking contrasts in weather patterns. In September, temperatures range from a mild 7°C (46°F) at night to a warm maximum of 33°C (92°F) during the day, accompanied by a comfortable humidity level of 71%. The month typically sees some precipitation, with about 92 mm (3.6 in) spread over 8 days. In contrast, February is marked by much colder conditions, featuring a chilling minimum of -16°C (4°F) and an average temperature of just 1°C (34°F). The maximum temperature reaches a more temperate 20°C (68°F), but with higher humidity at 84%, it can feel even colder. February also experiences slightly more precipitation, totaling 97 mm (3.8 in) across 10 days. For more details on this month's weather, check out Boston weather in February.
Comparing the weather in September and March reveals contrasting seasonal conditions. September typically experiences milder temperatures, with a minimum of 7°C (46°F) and an average of 19°C (67°F), peaked by highs reaching up to 33°C (92°F). In contrast, March is significantly colder, featuring minimum temperatures plunging to -12°C (11°F) and an average of just 3°C (38°F), with a maximum of 20°C (68°F). Both months see considerable precipitation, with September bringing in 92 mm (3.6 in) over 8 days, while March records slightly higher at 102 mm (4.0 in) across 10 days. Additionally, humidity levels are elevated in both months, at 71% for September and 82% for March, contributing to a heavier feel during spring's thaw. For more details on March specifics, you can check Boston weather in March.
When comparing the weather in September and April, it's clear that both months have distinct characteristics. September typically experiences milder temperatures, with averages around 19°C (67°F) and a maximum reaching up to 33°C (92°F), making it feel much warmer than April, which has an average temperature of only 9°C (48°F) and a maximum of 27°C (81°F). However, April sees more precipitation, totaling 135 mm (5.3 in) over approximately 13 days, compared to September's 92 mm (3.6 in) spread over 8 days. Additionally, the humidity is slightly higher in April at 80%, compared to September's 71%. For a detailed look at what April holds, check out Boston weather in April.
September and May exhibit distinct weather characteristics despite their proximity in the annual calendar. In September, average temperatures reach a pleasant 19°C (67°F), with maximum highs touching 33°C (92°F), while the minimum temperature is a milder 7°C (46°F). The month typically sees about 92 mm (3.6 in) of precipitation over approximately 8 days, and humidity hovers around 71%. In contrast, May offers cooler temperatures, with an average of 14°C (58°F) and maximums up to 31°C (89°F), alongside a lower minimum of 3°C (37°F). Rainfall is slightly higher in May at 94 mm (3.7 in) across 12 days, with humidity remaining comparable at 72%. For more information on the climate during this month, you can check Boston weather in May.
In comparing the weather of September to that of June, both months exhibit similar temperature ranges, with average temperatures hovering around 19°C (67°F) and maximums reaching up to 33°C (92°F). September experiences slightly cooler minimum temperatures, with lows of 7°C (46°F) compared to June's 8°C (47°F). Precipitation levels are also comparable, with September recording 92 mm (3.6 in) over about 8 days and June having 86 mm (3.4 in) over 10 days. Humidity remains fairly constant, with September at 71% and June at 72%. For more details on June weather conditions, you can check out Boston weather in June.
In comparing the weather between September and July, September experiences a broader temperature range with minimums dropping to 7°C (46°F) and maximums peaking at 33°C (92°F), while July maintains a warmer baseline, with minimums around 14°C (57°F) and maximums reaching 34°C (94°F). September also sees slightly less rainfall, with 92 mm (3.6 in) of precipitation on average over 8 days compared to July’s 115 mm (4.5 in) over 12 days. Additionally, humidity levels are slightly higher in September at 71% compared to July's 67%. For more insights into the summer heat, you can check Boston weather in July.
In comparing the weather of September and August, September presents a cooler climate with a minimum temperature of 7°C (46°F), contrasted with August's warmer minimum of 13°C (56°F). While both months see a peak temperature of 33°C (92°F), September's average temperature drops to 19°C (67°F) compared to August's 23°C (73°F). Precipitation levels are slightly higher in September at 92 mm (3.6 in) over 8 days, whereas August experiences 76 mm (3.0 in) over 10 days. Additionally, September exhibits greater humidity at 71%, while August maintains a lower level of 66%. For more detailed insights, check out Boston weather in August.
September typically experiences warmer temperatures, with a minimum of 7°C (46°F) and an average high reaching up to 33°C (92°F). In contrast, October sees a drop in temperatures, featuring a minimum of 0°C (33°F) and an average high of 27°C (81°F). September also has less precipitation, averaging 92 mm (3.6 in) over 8 days, while October receives more rainfall at 149 mm (5.9 in) across 12 days. Additionally, humidity rises slightly from 71% in September to 78% in October. For more details about October weather, you can visit Boston weather in October.
September brings a warm and inviting climate, with average temperatures reaching 19°C (67°F) and maximums soaring up to 33°C (92°F). The month sees considerable humidity at 71% and experiences around 92 mm (3.6 in) of precipitation over approximately 8 days. In contrast, November ushers in a much colder atmosphere, where average temperatures drop to 7°C (44°F), with minimums dipping as low as -10°C (14°F). Despite November's slightly higher precipitation of 100 mm (3.9 in) over 10 days, the humidity increases to 84%, creating a distinctly more brisk and damp environment. For more detailed insights, you can explore Boston weather in November.
September and December present a stark contrast in weather. In September, temperatures range from a mild 7°C (46°F) at night to a warm average of 19°C (67°F), peaking at 33°C (92°F), while December experiences much colder conditions with temperatures dropping to a frigid -16°C (3°F) at night and an average of just 2°C (36°F). Precipitation also differs, with September receiving 92 mm (3.6 in) over 8 days compared to December's higher 124 mm (4.9 in) over 10 days, contributing to an increase in humidity from 71% in September to 81% in December. For more insights on December weather, you can check Boston weather in December.
September in Boston marks a transition from the warmth of summer to the crispness of autumn, with temperatures averaging a comfortable 19°C (67°F), allowing for pleasant outdoor activities. While some days may peak at a sizzling 33°C (92°F), the nights can bring a refreshing coolness, dipping down to around 7°C (46°F). The month also sees a fair amount of humidity at 71%, contributing to a unique blend of warmth and coolness. With 8 days of rainfall totaling 92 mm (3.6 in), September can be somewhat wet, but it helps make way for the vibrant fall foliage that follows. For a deeper understanding of how September compares to other months, explore the details at Boston Climate.