September Weather in Falmouth, United States

Last updated: February 24, 2025

In September, Falmouth experiences a delightful transition from summer to fall, with average temperatures hovering around 20°C (67°F). The month sees a peak maximum of 25°C (78°F) and a cooler minimum of 14°C (57°F), creating a comfortable climate for outdoor activities. However, expect approximately 117 mm (4.6 in) of rainfall spread over 10 days, contributing to a rather humid atmosphere with humidity levels around 75%. This blend of warmth and moisture makes September an idyllic time to explore the vibrant coastal town while enjoying its scenic beauty.

September Temperature in Falmouth

In September, Falmouth begins to transition from the warm embrace of summer to the crispness of fall. With minimum temperatures averaging around 14°C (57°F) and maximums reaching up to 25°C (78°F), this month offers a delightful balance for outdoor enthusiasts. Surprisingly mild average highs of 20°C (67°F) invite locals and visitors alike to enjoy the outdoors before the chill of autumn sets in. Compared to the sweltering heat of July and August, where temperatures soar to the mid-20s, September's gradual cool-down signals the beginning of sweater weather, making it a perfect time for beach strolls and enjoying the changing foliage. As the month progresses, the region prepares for a cooler October, but September stands out as a comfortable retreat, blending the remnants of summer warmth with the impending crispness of fall.

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

The chart illustrates September temperature patterns in Falmouth, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec353638465463717267604940
Data source: Temperature data for Falmouth 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 Falmouth

In September, Falmouth experiences a notable shift in weather patterns, with precipitation reaching 117 mm (4.6 in) over approximately 10 days. This not only marks a slight increase from the drier months of July and August, which saw only 84 mm and 86 mm respectively, but also sets the stage for the wetter season ahead. The trend suggests a transition towards more consistent rainfall, contrasting with the summer's sporadic showers. As autumn approaches, the rain prepares the landscape for vibrant fall colors, illustrating nature's beautiful cycle of change. This month acts as a reminder of the impending shift, leading into one of the rainiest months of the year, October, with its expected 168 mm (6.6 in) of precipitation.

September Precipitation Trends in Falmouth

The chart displays monthly precipitation patterns in Falmouth, 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.
JanFebMarAprMayJunJulAugSepOctNovDec93118116134119908486117168103129
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Falmouth

In September, Falmouth experiences a slight dip in humidity, averaging around 75%, which reflects the transition from the more humid summer months. Following the peak humidity of around 84% in the winter months of January and February, levels gradually decrease through the spring and summer. By the time September rolls in, the humidity stabilizes at its lower range, paralleling the consistent 75% seen in October. This trend indicates a gradual shift towards drier air as the region moves into fall, setting the stage for a more comfortable atmosphere as temperatures begin to cool. Overall, September serves as a gentle bridge between the sticky heat of summer and the crispness of autumn.

September Average Humidity in Falmouth

This chart illustrates the average monthly humidity levels in Falmouth, 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 Falmouth

As September rolls into Falmouth, the UV Index remains notably high at 8, categorizing it as very high and resulting in a burn time of just 15 minutes. This indicates a slight decrease from the peak of summer, where UV levels reached 10 in June, but still emphasizes the need for sun protection during outdoor activities. The trend through the months clearly illustrates a seasonal variation: after a high concentration of UV exposure in the summer, the figures begin to decline into the cooler fall months. Remember to stay vigilant with sun safety strategies as the sun's strength can still pose risks in early autumn. For more detailed insights, check out the Falmouth UV Index.

Maximum UV Index Levels in Falmouth for September

The chart shows the monthly maximum UV Index (UVI) for Falmouth 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: Falmouth 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 Falmouth

In Falmouth, September bathes in a warm glow, contributing a delightful 280 hours of sunshine to the year's total. As summer gradually slips away, the sunshine hours begin to taper off from the peak of 346 hours in July. This month still holds onto the remnants of the vibrant summer, showing brighter days compared to the lush months of spring, like April at 243 hours. However, the transition into autumn is evident as the light starts to dim, foreshadowing the cooler months ahead with October seeing a drop to 236 hours. The gradual decline in sunshine hours reminds us of the cyclical nature of the seasons, creating a perfect backdrop for Falmouth's beautiful fall landscapes.

Monthly Sunshine Duration in Falmouth: September Highlighted

The September sunshine duration represents the total number of hours Falmouth 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: Falmouth September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Falmouth During September

In Falmouth, September marks a notable shift in weather patterns, with a 50% chance of sunny days—a refreshing improvement compared to the summer months. As the humidity of July and August wanes, residents and visitors can look forward to a more balanced atmosphere, allowing for outdoor activities and vibrant fall festivities. Interestingly, September’s sunny probability aligns closely with the 45% forecast in October and rises above the earlier summer months, indicating a promising transition into autumn. This seasonal change not only offers a delightful opportunity to enjoy the outdoors but also reflects the town's beautiful scenery as leaves begin to turn.

Percentage of Sunny Days in September in Falmouth

The chart illustrates the percentage of sunny days in Falmouth 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 Falmouth experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec41%31%60%46%41%38%41%36%50%45%54%29%
Data source: Falmouth September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Falmouth in September

As summer gracefully transitions into fall, September in Falmouth brings a noteworthy shift in daylight, offering around 12 hours of sunshine each day. This marks a subtle decline from the sun-drenched peak of 15 hours in June, reflecting the inevitable change in seasons. The month serves as a gentle reminder of the days getting shorter, following a gradual descent from the 14 hours of daylight in July and 13 hours in August. As nature begins to prepare for the cooler months, this moderate daylight serves as the perfect backdrop for enjoying the vibrant autumn colors that soon emerge.

Average Daylight Hours in Falmouth for September

The chart illustrates the variation in daylight duration in Falmouth throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 32m10h 36m11h 58m13h 21m14h 32m15h 7m14h 48m13h 45m12h 25m11h 2m9h 49m9h 12m
Data source: Falmouth daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Falmouth

As summer fades into autumn, September in Falmouth brings a gentle breeze that contrasts notably with the brisk winds of earlier months. With an average wind speed of 5.9 m/s (13 mph), it marks a slight uptick from August's lull, yet still feels refreshing. This month is nestled between the lower winds of July and August, where the breezes relaxed to 5.2 m/s and 4.9 m/s respectively. September's winds begin to prepare the area for the lively gusts of fall, hinting at the transition that lies ahead, as average speeds steadily rise again into October and November, reaching 6.6 m/s (15 mph). This inviting shift not only enriches the coastal experience but also heralds the beauty of changing seasons.

Average September Wind Speed in Falmouth

The chart displays monthly wind speed patterns in Falmouth, 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.
JanFebMarAprMayJunJulAugSepOctNovDec6.86.76.86.56.16.15.24.95.9 m/s6.66.66.4
Data source: Falmouth September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Falmouth Compares to Other Months

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

September and January weather showcase a stark contrast in temperature and conditions. In September, the temperatures range from a minimum of 14°C (57°F) to a maximum of 25°C (78°F), with an average of 20°C (67°F). This month experiences considerable rainfall, with 117 mm (4.6 in) of precipitation over approximately 10 days and a humidity level of 75%. In contrast, January is much colder, featuring temperatures that drop to a minimum of -16°C (4°F) and reach a maximum of 13°C (55°F), with an average temperature of just 2°C (35°F). Despite having slightly less precipitation at 93 mm (3.7 in) over 9 days, January is characterized by a higher humidity of 84%. For more detailed insights, you can visit Falmouth weather in January.

September and February present strikingly different weather conditions. In September, temperatures range from a mild 14°C (57°F) at night to a warm average of 20°C (67°F) during the day, reaching up to 25°C (78°F) at its peak. With 117 mm (4.6 in) of precipitation over approximately 10 days, the humidity averages around 75%, creating a relatively comfortable atmosphere. In contrast, February is characterized by much colder weather, with temperatures plunging to a low of -12°C (11°F) and averaging just 2°C (36°F), peaking at a maximum of 12°C (53°F). Though it also sees similar precipitation levels of 118 mm (4.6 in) over about 12 days, the humidity is higher at 84%, resulting in a much chillier feel. For a more detailed look at February weather, you can check Falmouth weather in February.

When comparing the weather in September and March, it's evident that September is considerably warmer, with average temperatures ranging from a minimum of 14°C (57°F) to a maximum of 25°C (78°F), while March experiences much cooler temperatures, averaging between -9°C (17°F) and 13°C (55°F). Both months see similar levels of precipitation, around 116-117 mm (4.6 in), and approximately 10 days of rain; however, March has a higher humidity level at 82%, compared to September's 75%. For more details on March weather, you can visit Falmouth weather in March.

September generally offers warmer temperatures compared to April, with averages around 20°C (67°F) and highs reaching 25°C (78°F), while April sees much cooler averages of 8°C (46°F) with maximum temperatures only hitting 16°C (61°F). Although both months experience similar levels of precipitation, September has slightly less rainfall at 117 mm (4.6 in) over 10 days, whereas April has 133 mm (5.3 in) of rain over 12 days. Additionally, September has a lower humidity level at 75%, compared to April's 79%, making the former feel a bit more comfortable. For a detailed look at April weather, you can check Falmouth weather in April.

September and May present contrasting weather patterns, with September typically enjoying warmer temperatures. In September, the minimum temperature hovers around 14°C (57°F), while the average reaches 20°C (67°F), peaking at 25°C (78°F). In contrast, May experiences cooler conditions, with a minimum of 4°C (40°F), an average of 12°C (54°F), and a maximum of 20°C (67°F). Both months receive similar amounts of precipitation—117 mm (4.6 in) in September and 119 mm (4.7 in) in May—but September sees rain over 10 days compared to May's 13 days. Interestingly, both months maintain a consistent humidity level of 75%. For more details on May weather, visit Falmouth weather in May.

When comparing the weather in September and June, September tends to be slightly warmer with average temperatures reaching 20°C (67°F) compared to June's 17°C (63°F). The maximum temperature in September can reach up to 25°C (78°F), making it a bit more inviting for outdoor activities, whereas the maximum in June is 23°C (74°F). However, September is also wetter, receiving about 117 mm (4.6 in) of precipitation over approximately 10 days, compared to June's 90 mm (3.5 in) with similar rainfall days. Humidity levels are quite comparable, with September at 75% and June at 78%, indicating a comfortably humid atmosphere in both months. For more details, you can check Falmouth weather in June.

In comparing September and July weather, September tends to be slightly cooler, with minimum temperatures of 14°C (57°F) compared to July's 16°C (61°F). Average temperatures in September also sit at 20°C (67°F), while July enjoys a warmer average of 22°C (71°F). Although both months experience high humidity, September's level is a touch higher at 75%, versus July's 76%. Precipitation is more pronounced in September, with 117 mm (4.6 in) over 10 days, compared to July’s 84 mm (3.3 in) over 9 days. For further details on July weather in Falmouth, check out Falmouth weather in July.

In comparing the weather of September and August, September sees slightly cooler temperatures, with a minimum of 14°C (57°F) compared to August's minimum of 17°C (63°F). The average temperature in September is 20°C (67°F), down from August's 22°C (73°F). While September experiences increased precipitation at 117 mm (4.6 in) over 10 days, August has less rain at 86 mm (3.4 in) across 9 days, making it drier overall. Humidity remains fairly consistent, with September at 75% and August at 76%. For a more detailed look at August's climate, visit Falmouth weather in August.

September weather is generally warmer, with average temperatures around 20°C (67°F) and maximums peaking at 25°C (78°F). In contrast, October sees a significant drop, with average temperatures around 15°C (60°F) and minimums hovering around 4°C (39°F). Additionally, October experiences more precipitation than September, with 168 mm (6.6 in) over 12 days compared to September's 117 mm (4.6 in) over 10 days. Both months share a humidity level of 75%, but the cooler temperatures of October provide a different atmosphere. For more details about October weather, you can check this link: Falmouth weather in October.

September and November showcase a significant shift in weather characteristics. In September, temperatures range from a mild 14°C (57°F) at night to a warm 25°C (78°F) during the day, with an average of 20°C (67°F). The month experiences considerable rainfall, totaling 117 mm (4.6 in) over about 10 days, and maintains a humidity level of 75%. In contrast, November brings much cooler temperatures, with a minimum of -6°C (21°F) and an average of only 9°C (49°F). The maximum temperature in November can reach 19°C (67°F), while precipitation slightly decreases to 103 mm (4.0 in) over the same 10 days, and humidity rises to 80%. This shift from the warmth of September to the chill of November marks a notable transition in the seasonal climate. For more details, check out Falmouth weather in November.

September weather is characterized by mild temperatures, with averages around 20°C (67°F) and maximums reaching up to 25°C (78°F). In contrast, December sees a significant drop in temperatures, with averages plummeting to just 4°C (40°F) and minimums dipping as low as -12°C (11°F). Precipitation is relatively high in both months, with September receiving 117 mm (4.6 in) over 10 days and December slightly higher at 129 mm (5.1 in) over 11 days. Additionally, December tends to be more humid, with humidity levels reaching 80%, compared to September's 75%. For more detailed information, you can check Falmouth weather in December.

Compare Falmouth's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Falmouth

As September rolls in, Falmouth experiences a transition marked by mild temperatures and noticeable humidity. With highs around 25°C and lows dipping to 14°C, the month offers a comfortable climate that contrasts with the sweltering days of summer. While it sees a moderate level of precipitation, with about 10 days of rain, the overall ambiance remains pleasant. This blend of warmth and moisture sets September apart, making it an ideal time for outdoor activities before the crispness of autumn settles in. For a deeper dive into the seasonal shifts, explore more at Falmouth Climate.