September Weather in Barnstable, United States

Last updated: February 24, 2025

In September, Barnstable experiences a delightful transition into fall, with an average temperature around 19°C (67°F), peaking at a comfortable 25°C (78°F) during the warmest days and dipping to a mild 13°C (56°F) at night. This month also brings 118 mm (4.7 in) of rainfall over approximately 10 days, contributing to the area's lush greenery. Humidity levels hover around 75%, creating a pleasantly crisp atmosphere perfect for outdoor activities and enjoying the scenic beauty of the season. Whether you're strolling along the beaches or exploring local trails, September in Barnstable showcases the charm of late summer into autumn.

September Temperature in Barnstable

As summer transitions to fall, September in Barnstable showcases a delightful shift in temperatures. With minimums around 13°C (56°F) and maximums peaking at 25°C (78°F), the weather remains pleasantly warm yet begins to hint at the cooling of autumn. This month boasts an average temperature of 19°C (67°F), providing a comfortable backdrop for outdoor activities and the vibrant changing foliage. Compared to the sweltering heights of July and August, September strikes a harmonious balance, making it a perfect time for locals and visitors alike to enjoy the natural beauty and charm of Barnstable before the cooler months settle in.

September Weather in Barnstable: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Barnstable, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec353638455363707266594839
Data source: Temperature data for Barnstable generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Barnstable

In September, Barnstable experiences a noteworthy average precipitation of 118 mm (4.7 inches), mirroring the rainfall seen earlier in the spring months. With 10 days of precipitation recorded, this month's wetness signifies a transition from the drier summer months of July and August, which have lower totals of 83 mm (3.3 inches) and 82 mm (3.2 inches), respectively. As autumn sets in, September's rainfall prepares the region for the more significant 175 mm (6.9 inches) expected in October, highlighting a seasonal pattern where fall delivers more moisture compared to the summer heat. This cyclical shift not only refreshes the landscape but also sets the stage for the lush colors of fall.

September Precipitation Trends in Barnstable

The chart displays monthly precipitation patterns in Barnstable, with values for each month alongside September's data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September's conditions compare to those of other months.
JanFebMarAprMayJunJulAugSepOctNovDec94123118137119918382118175102136
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Barnstable

In September, Barnstable experiences a notable shift in humidity levels, with an average of 75%. This marks a gradual decline from the summer months, where humidity peaked at 76% in both July and August. As the year transitions into fall, the trend of decreasing humidity continues, paralleling a drop from the warmer, more humid days of summer. This easing of moisture in the air not only offers a reprieve from the sticky heat but also signals the impending arrival of crisper autumn weather, setting the stage for a more comfortable outdoor experience.

September Average Humidity in Barnstable

This chart illustrates the average monthly humidity levels in Barnstable, with September's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how September's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec84%84%82%79%75%78%76%76%76%75%80%80%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Barnstable

As summer transitions into fall, September in Barnstable maintains a very high UV Index of 8, indicating that sun protection is still essential for outdoor activities. This month sees a slight decrease compared to the peak of summer, yet the burn time remains quick at just 15 minutes. Throughout the year, we've observed a clear trend of increased UV exposure during the warmer months, with January's index starting at a moderate 3. With September's robust UV levels, it’s crucial to stay vigilant about sun safety to enjoy the remaining sunny days. For more detailed information on UV levels, visit Barnstable UV Index.

Maximum UV Index Levels in Barnstable for September

The chart shows the monthly maximum UV Index (UVI) for Barnstable in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec3468910998642
Data source: Barnstable September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

September Sunshine in Barnstable

As summer gracefully transitions into fall, September in Barnstable, United States, enjoys a delightful 280 hours of sunshine, a remarkable glow that reflects the seasonal shift. This month marks a reduction from the sun-drenched peak of July and August, yet it still boasts an impressive amount compared to the winter months like January with just 142 hours. The gradual decrease in daylight hours after the sunniest months signifies a period of change, where the warmth of summer lingers just long enough to invite outdoor adventures, making September a favorite for enjoying the tail end of the season. With May and June delivering the highest sunshine totals leading into the summer, the gradual decline leading into October reveals a poignant beauty, reminding us to savor these golden days before the chill sets in.

Monthly Sunshine Duration in Barnstable: September Highlighted

The September sunshine duration represents the total number of hours Barnstable experiences direct sunlight during the month of September, excluding cloudy or obstructed periods. This chart compares the sunshine duration of September with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec142h184h258h243h298h326h346h330h280h236h203h165h
Data source: Barnstable September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Barnstable During September

In September, Barnstable enjoys a notable increase in the likelihood of sunny weather, with a 49% chance of sunshine illuminating the early days of fall. This statistic positions September among the more favorable months for sunlight, standing out from the lower percentages of summer months like July and August, which hover around 35-37%. Interestingly, as the year progresses, September transitions from the cooler summer months to a steadier chance of clear skies, reflecting a trend where the chances of sun generally fluctuate. This makes September a delightful time for outdoor activities, as residents and visitors can anticipate more frequent sunny days before the clouds of autumn set in.

Percentage of Sunny Days in September in Barnstable

The chart illustrates the percentage of sunny days in Barnstable throughout the year, with September highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Barnstable experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec36%28%57%43%41%38%37%35%49%44%52%28%
Data source: Barnstable September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Barnstable in September

As summer gracefully transitions into fall, September in Barnstable, United States, brings a modest reduction in daylight, offering 12 hours of light. This decrease follows a peak of 15 hours in June, showcasing a gradual decline as the days shorten. The month acts as a gentle reminder of the changing seasons, as daylight hours shift from the vibrant, sun-filled days of summer, with July at 14 hours and August at 13 hours, to the beginnings of autumn's embrace. The pattern is clear: after a lively stretch of long days, September marks the start of a more subdued daylight experience, paving the way for the cozy allure of cooler months ahead.

Average Daylight Hours in Barnstable for September

The chart illustrates the variation in daylight duration in Barnstable throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 31m10h 36m11h 58m13h 22m14h 33m15h 8m14h 49m13h 45m12h 25m11h 1m9h 48m9h 11m
Data source: Barnstable daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Barnstable

As September sweeps into Barnstable, the winds begin to shift, bringing a refreshing change after the quieter summer months. The average wind speed rises slightly to 5.9 m/s (13 mph), marking a transition from the gentle breezes of August, which enjoyed a lull at 4.8 m/s (11 mph). This increase signifies the gradual return of invigorating winds that characterize the fall season. The data reveals a consistent pattern where wind speeds generally strengthen as the year progresses towards autumn. While September's winds may not reach the vigor seen in the winter months, they provide a perfect backdrop for outdoor activities, inviting residents and visitors alike to relish the crisp air and vibrant landscapes of early fall.

Average September Wind Speed in Barnstable

The chart displays monthly wind speed patterns in Barnstable, with values for each month shown alongside September's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how September's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec7.17.27.06.55.96.25.24.85.9 m/s6.66.76.6
Data source: Barnstable September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Barnstable Compares to Other Months

The weather in Barnstable 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 Barnstable and find detailed weather information for every month.

September and January present stark contrasts in weather. September typically enjoys milder temperatures, with an average around 19°C (67°F) and highs reaching up to 25°C (78°F), while January faces much colder conditions, averaging just 2°C (36°F) and with maximums only hitting 13°C (55°F). Precipitation is also notable in both months, with September receiving 118 mm (4.7 in) over about 10 days, while January has slightly less at 94 mm (3.7 in), also across 10 days. Additionally, January's higher humidity at 84% compared to September's 75% adds to the chill in the air. For more detailed information, you can check Barnstable weather in January.

September and February present starkly contrasting weather conditions. In September, temperatures range from a minimum of 13°C (56°F) to a maximum of 25°C (78°F), with an average of 19°C (67°F), while February is significantly colder, with temperatures plummeting to a minimum of -12°C (10°F) and peaking at just 11°C (53°F), averaging around 2°C (36°F). Both months experience notable precipitation, with September seeing 118 mm (4.7 in) over 10 days and February receiving slightly more at 123 mm (4.8 in) over 12 days. Additionally, the humidity is higher in February at 84% compared to September's 75%, contributing to the winter's chill. For more detailed insights into February’s weather conditions, you can visit Barnstable weather in February.

When comparing the weather in September to March, there is a striking contrast in temperatures and overall climate. September enjoys milder conditions with an average temperature of 19°C (67°F), peaking at a comfortable 25°C (78°F). In contrast, March experiences much colder temperatures, with an average of only 3°C (38°F) and a maximum of 13°C (56°F). Both months receive similar amounts of precipitation, around 118 mm (4.7 in) over approximately 10 days, but humidity levels are slightly higher in March at 82% compared to September's 75%. For more detailed information, you can check out Barnstable weather in March.

September and April present contrasting weather patterns. In September, temperatures are milder with minimums around 13°C (56°F) and average highs reaching up to 25°C (78°F), making it a pleasant month for outdoor activities. The precipitation in September totals 118 mm (4.7 in) over approximately 10 days, resulting in a relatively humid environment at 75%. In comparison, April experiences cooler temperatures, with a minimum of 1°C (33°F) and an average maximum of only 16°C (60°F), making it a much chillier month. Notably, April sees slightly higher precipitation at 137 mm (5.4 in) over 13 days and a humidity level of 79%. For more details on April weather, you can check Barnstable weather in April.

When comparing the weather in September and May, it’s evident that September generally offers warmer temperatures. In September, temperatures range from a minimum of 13°C (56°F) to a maximum of 25°C (78°F), with an average of 19°C (67°F). In contrast, May sees cooler conditions, with temperatures ranging from a minimum of 5°C (41°F) to a maximum of 21°C (70°F) and an average of 12°C (53°F). Both months experience similar levels of precipitation, with September receiving 118 mm (4.7 in) over about 10 days and May slightly higher at 119 mm (4.7 in) over 12 days. Humidity levels remain consistent at 75% for both months. For more specific insights into Barnstable's weather in May, you can explore Barnstable weather in May.

In comparing the weather of September and June, we see some notable differences. September typically offers slightly warmer temperatures, with an average of 19°C (67°F) compared to June's 17°C (63°F). The maximum temperatures in September can reach up to 25°C (78°F), while June's maximum is a bit lower at 24°C (76°F). Rainfall is more abundant in September, accumulating to 118 mm (4.7 in) over 10 days, whereas June sees a total of 91 mm (3.6 in) for the same number of days. Additionally, September tends to have a slightly lower humidity level at 75% compared to June's 78%. For more detailed information about June weather, you can check Barnstable weather in June.

When comparing the weather in September to July, we see notable differences in both temperature and precipitation. September brings cooler temperatures, with average highs of 25°C (78°F) compared to July's warmer maximum of 29°C (84°F). Additionally, September experiences more precipitation, accumulating 118 mm (4.7 in) over 10 days, while July receives 83 mm (3.3 in) over 9 days. Humidity remains relatively consistent between the two months, with September at 75% and July slightly higher at 76%. For a more detailed look at July weather, you can visit this link: Barnstable weather in July.

In comparing the weather conditions of September and August, September tends to be slightly cooler, with average temperatures ranging from a minimum of 13°C (56°F) to a maximum of 25°C (78°F), compared to August's warmer range of 16°C (61°F) min to 27°C (81°F) max. Precipitation is more frequent in September, with 118 mm (4.7 in) falling over 10 days, whereas August experiences less rainfall, totaling 82 mm (3.2 in) over 8 days. Humidity remains relatively consistent between the two months, with September at 75% and August at 76%. For a more detailed look at the weather, check out Barnstable weather in August.

September typically experiences milder temperatures with average highs around 25°C (78°F) and lows of 13°C (56°F), accompanied by 118 mm (4.7 in) of precipitation over about 10 days. In contrast, October sees a notable drop in temperatures, with average highs of 22°C (72°F) and lows plunging to 4°C (39°F). Precipitation increases as well, totaling 175 mm (6.9 in) across 12 days, while humidity levels remain consistent at 75%. For more details on October weather, you can check Barnstable weather in October.

September and November display contrasting weather patterns, reflecting the transition from summer to autumn. In September, temperatures range from a minimum of 13°C (56°F) to a maximum of 25°C (78°F), with an average of 19°C (67°F). The month sees significant rainfall, totaling 118 mm (4.7 in) across 10 days, and relative humidity sits at 75%. In contrast, November experiences much cooler weather with temperatures dipping to a minimum of -6°C (21°F) and an average of 9°C (48°F), reaching a maximum of 19°C (66°F). Although it has slightly less rainfall at 102 mm (4.0 in) over the same number of days, humidity increases to 80%. For more specific insights on November weather, you can check Barnstable weather in November.

September and December exhibit stark contrasts in weather patterns. In September, temperatures range from a mild 13°C (56°F) to a warm 25°C (78°F), with an average of 19°C (67°F), while December experiences much colder conditions, with temperatures dipping as low as -12°C (11°F) and averaging only 4°C (40°F). Precipitation levels are fairly similar, with September receiving 118 mm (4.7 in) over 10 days and December slightly higher at 136 mm (5.4 in) over 12 days. Additionally, humidity is higher in December at 80%, compared to September's 75%. For further insights, you can check out Barnstable weather in December.

Compare Barnstable's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Barnstable

As September unfolds in Barnstable, the weather marks a delightful transition towards autumn, with temperatures cooling from the summer heat. Unlike the sweltering highs of July and August, September's average temp brings a refreshing warmth, tempering the excitement of outdoor activities with a touch of crispness in the air. However, it's not just the temperature that sets this month apart; the increased precipitation, which spreads across about a third of the month, adds to the lushness of the landscape, making it a vibrant time to explore. Coupled with humidity levels around 75%, September provides a unique blend of warm and damp days, ideal for enjoying the natural beauty of the region. For those keen on understanding Barnstable's climate nuances, including the delightful changes September brings, visit Barnstable Climate.