September Weather in Mystic, United States

Last updated: February 24, 2025

In September, Mystic, United States, experiences a delightful transition into autumn with an average temperature of 20°C (68°F), peaking at a comfortable 27°C (82°F). As the month unfolds, temperatures cool down to a nightly minimum of 10°C (51°F), making evenings cozy and inviting. With approximately 101 mm (4.0 in) of rainfall spread over 9 days, the air remains refreshingly humid at 75%, adding a touch of mystique to the scenic charm of the region. This combination of mild temperatures and periodic rain makes September an ideal time to explore Mystic's vibrant landscapes and rich history.

September Temperature in Mystic

In September, Mystic, United States, experiences a pleasant transition from the summer heat to the cooler days of autumn. With minimum temperatures averaging around 10°C (51°F) and maximums reaching up to 27°C (82°F), the month is characterized by a comfortable afternoon warmth and refreshing evenings. The average temperature sits at a balmy 20°C (68°F), making it an ideal time for outdoor activities and enjoying the scenic beauty as the leaves start to change. This shift in temperature signals the approach of fall, providing a delightful mix of warm days and cooler nights, setting the stage for the stunning autumn foliage that Mystic is known for.

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

The chart illustrates September temperature patterns in Mystic, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec353639465564727268604840
Data source: Temperature data for Mystic 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 Mystic

September in Mystic, United States, brings a steady precipitation pattern, with 101 mm (4.0 in) of rain falling over 9 days. This aligns closely with the preceding months, particularly August, which also registered 101 mm of rainfall. As summer transitions into fall, September maintains a moderate level of moisture, hinting at the impending changes as October typically ramps up precipitation significantly, averaging 157 mm (6.2 in). While September's rainfall is consistent, the gradual increase towards autumn sets the stage for a wetter season ahead, underscoring a trend of rising precipitation as the year winds down.

September Precipitation Trends in Mystic

The chart displays monthly precipitation patterns in Mystic, 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.
JanFebMarAprMayJunJulAugSepOctNovDec8310910813611984115101101157113141
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Mystic

As summer transitions into autumn, September in Mystic witnesses a subtle yet notable shift in humidity levels, settling at around 75%. This marks a gradual decline from the higher humidity of the preceding months, where it hovered mostly in the mid to high seventies. The trend shows that September's humidity is slightly lower than August's, reflecting the typical seasonal change and providing a hint of crispness in the air. Following a summer of relatively humid weather, this decrease sets the stage for the upcoming months, which will maintain a similar comfort level at 75% in October, before climbing again in November. Overall, September serves as a smooth transition into the more temperate conditions of the fall, offering a pleasant balance that's both refreshing and inviting.

September Average Humidity in Mystic

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

As we transition into September in Mystic, the UV Index exhibits a notable decline from the peak summer months, settling at 8, which falls under the very high exposure category. This marks a slight drop from the intense 10 registered in both July and June, yet it still signifies that sun protection remains crucial, with a burn time of just 15 minutes. Throughout the year, the UV Index has shown a consistent pattern of increasing intensity from winter through summer, reaching its zenith during the peak months of June and July, before tapering off in the fall. As the days shorten and temperatures cool, it’s essential to stay vigilant about sun safety during this period of declining but still elevated UV levels. For more detailed insights on UV exposure, visit Mystic UV Index.

Maximum UV Index Levels in Mystic for September

The chart shows the monthly maximum UV Index (UVI) for Mystic 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.
JanFebMarAprMayJunJulAugSepOctNovDec35689101098642
Data source: Mystic 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 Mystic

In September, the sun continues to shine brightly on Mystic, United States, contributing a robust 282 hours of sunlight, marking a delightful transition into autumn. As summer fades, the hours of sunshine gradually decrease from the peak of 351 hours in July, yet September still boasts a generous amount of daylight compared to earlier months. This trend emphasizes the lingering warmth of summer, providing residents and visitors alike with the perfect backdrop for outdoor activities and scenic explorations. With the sunlight slowly retreating as the year progresses—trending downward to 175 hours by December—September serves as a beautiful bridge, allowing one last taste of summer's brilliance before yielding to the cooler days ahead.

Monthly Sunshine Duration in Mystic: September Highlighted

The September sunshine duration represents the total number of hours Mystic 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.
JanFebMarAprMayJunJulAugSepOctNovDec152h187h263h254h295h324h351h331h282h232h207h175h
Data source: Mystic September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Mystic During September

September in Mystic, United States, presents a balanced opportunity for sun lovers, with a 47% chance of sunny days. As summer gives way to autumn, the likelihood of sunshine remains relatively stable compared to the fluctuation seen in earlier months. While March boasts the highest sun probability at 61%, the dip in July and August, coupled with a rebound in October (46%), indicates that September stands as a somewhat reliable transition month for outdoor activities. With moderate sun potential, this month invites both relaxation and exploration, making it a delightful time to enjoy the natural beauty of the region.

Percentage of Sunny Days in September in Mystic

The chart illustrates the percentage of sunny days in Mystic 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 Mystic experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec49%31%61%47%44%40%43%34%47%46%54%33%
Data source: Mystic September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Mystic in September

As summer fades into autumn, September in Mystic, United States, ushers in a gentle decline in daylight, offering about 12 hours of sunlight. This transition marks a noticeable shift from the sun-drenched days of summer, with July and June basking in approximately 14 to 15 hours of daylight. Following the peak of brightness, August retains some warmth with 13 hours, before September continues the gradual descent into shorter days. This pattern reflects the changing seasons as the lush vibrancy of summer gives way to the inviting hues of fall, reminding us that even as the days grow shorter, the beauty of the season is just beginning to unfold.

Average Daylight Hours in Mystic for September

The chart illustrates the variation in daylight duration in Mystic throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 33m10h 37m11h 58m13h 21m14h 31m15h 5m14h 46m13h 44m12h 25m11h 2m9h 50m9h 13m
Data source: Mystic daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Mystic

As September unfolds in Mystic, United States, a noticeable shift in the wind greets residents and visitors alike. With an average wind speed of 5.2 m/s (12 mph), September marks a slight uptick from the summer lull, which saw July and August languishing at 4.2 m/s (9 mph). This gentle breeze prepares the way for autumn, as the winds begin to regain strength heading into the fall months. Interestingly, this trend of increasing wind speed continues into October, peaking at 5.8 m/s (13 mph), before establishing a consistent rhythm through November and December. September's winds, therefore, serve as a transitional whisper, bridging the relaxed tempo of summer with the brisk, spirited gusts that characterize the approaching seasons.

Average September Wind Speed in Mystic

The chart displays monthly wind speed patterns in Mystic, 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.
JanFebMarAprMayJunJulAugSepOctNovDec6.26.26.05.55.34.94.24.25.2 m/s5.85.85.8
Data source: Mystic September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Mystic Compares to Other Months

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

September and January present a stark contrast in weather conditions. In September, temperatures range from a mild 10°C (51°F) to a warm 27°C (82°F), with an average of 20°C (68°F), making it a pleasant month for outdoor activities. In contrast, January experiences much colder temperatures, with a minimum of -16°C (4°F) and a maximum of 14°C (58°F), resulting in an average of just 2°C (35°F). Both months see a similar number of rainy days, with September receiving 101 mm (4.0 in) over 9 days and January slightly less at 83 mm (3.3 in) across 8 days. Additionally, January is slightly more humid at 84%, compared to September’s 75%. For more insights into January's weather, check out this link: Mystic weather in January.

The weather in September is generally warm and pleasant, with average temperatures around 20°C (68°F) and highs reaching up to 27°C (82°F). It's a month characterized by relatively moderate humidity at 75% and some rainfall, with about 101 mm (4.0 in) spread over 9 days. In contrast, February presents a starkly different picture, with much colder temperatures that average only 2°C (36°F) and reach a maximum of 12°C (54°F). The month experiences higher humidity at 84% and slightly more precipitation, totaling 109 mm (4.3 in) over 11 days. For more insights on February weather, you can check Mystic weather in February.

September and March showcase contrasting weather patterns, with September offering warmer temperatures that range from a minimum of 10°C (51°F) to a pleasant average of 20°C (68°F), and a maximum reaching 27°C (82°F). In contrast, March is significantly colder, featuring minimum temperatures that can plummet to -9°C (16°F), an average of just 4°C (39°F), and a maximum of 15°C (60°F). Both months experience a similar level of precipitation, with September contributing 101 mm (4.0 in) over 9 days and March showing slightly higher rainfall at 108 mm (4.3 in) across the same number of days. Humidity is also notable, being slightly lower in September at 75% compared to March’s 82%. For those curious about the specific conditions prevalent during this time, check out Mystic weather in March.

In September, the weather tends to be warmer with average temperatures around 20°C (68°F) and maximums reaching up to 27°C (82°F), while April features much cooler conditions, with averages near 8°C (47°F) and maximums not exceeding 18°C (65°F). Precipitation is more frequent in April, totaling 136 mm (5.3 in) over about 12 days, compared to September’s 101 mm (4.0 in) over 9 days. Humidity levels are relatively similar, hovering around 75% in September and slightly higher at 79% in April. For more details on the conditions in April, you can visit Mystic weather in April.

When comparing the weather in September and May, September typically enjoys warmer temperatures, with minimums around 10°C (51°F) and maximums reaching up to 27°C (82°F), while May begins cooler, with minimums around 3°C (38°F) and a maximum of 22°C (72°F). Both months experience a similar humidity level of 75%, contributing to a relatively comfortable atmosphere. However, September tends to have slightly less precipitation, averaging 101 mm (4.0 in) over about 9 days, compared to May's 119 mm (4.7 in) over approximately 13 days. For a closer look at the weather specifics in May, you can check Mystic weather in May.

In comparing the weather of September and June, we notice a few key differences. September tends to be warmer, with an average temperature of 20°C (68°F) compared to June's average of 18°C (64°F). Additionally, the maximum temperatures in September reach up to 27°C (82°F), while June peaks at 25°C (78°F). However, September also experiences more precipitation, totaling 101 mm (4.0 in) over 9 rainy days, slightly higher than June's 84 mm (3.3 in) over 10 days. Humidity levels are similar in both months, with September at 75% and June slightly higher at 78%. For more information on June weather in Mystic, you can visit Mystic weather in June.

In comparing the weather between September and July, we can see a noticeable shift in temperatures and precipitation patterns. September features cooler conditions, with a minimum temperature of 10°C (51°F), an average of 20°C (68°F), and a maximum of 27°C (82°F). This month also experiences about 101 mm (4.0 in) of precipitation over 9 days, accompanied by a humidity level of 75%. In contrast, July is warmer, with minimum temperatures of 15°C (59°F), an average of 22°C (72°F), and a maximum of 29°C (85°F). The precipitation in July is slightly higher at 115 mm (4.5 in) over 10 days, with a comparable humidity of 76%. For a more in-depth look at the climatic conditions during July, check out Mystic weather in July.

Comparing the weather in September to August reveals some notable differences. September tends to be cooler, with minimum temperatures dropping to 10°C (51°F), while August remains warmer with a minimum of 15°C (60°F). The average temperature in September is 20°C (68°F), slightly lower than August's average of 22°C (73°F). Both months experience the same amount of precipitation, with 101 mm (4.0 in) falling over 9 days, and humidity levels are also quite similar, at 75% in September and 76% in August. For a detailed look at August's weather in Mystic, you can check out Mystic weather in August.

September and October exhibit distinct differences in weather patterns. In September, temperatures range from a mild 10°C (51°F) at night to a comfortable average of 20°C (68°F) during the day, peaking at 27°C (82°F). Meanwhile, October brings a noticeable drop in temperatures, with a minimum of 4°C (39°F) and an average of 16°C (60°F), while the maximum reaches 25°C (77°F). Precipitation also increases from September's 101 mm (4.0 in) over 9 days to 157 mm (6.2 in) across 12 days in October, maintaining the same humidity level of 75%. For a detailed look at what to expect, check out the Mystic weather in October.

September and November exhibit notable contrasts in weather patterns. September boasts milder temperatures, ranging from a minimum of 10°C (51°F) to a maximum of 27°C (82°F), with an average of 20°C (68°F). The month experiences 101 mm (4.0 in) of precipitation over 9 days and enjoys a relatively comfortable humidity level of 75%. In contrast, November witnesses a significant drop in temperatures, with a minimum of -7°C (20°F) and an average of 9°C (49°F), peaking at 20°C (68°F). Precipitation slightly increases to 113 mm (4.4 in) spread across 10 days, accompanied by a higher humidity level of 80%. For more detailed insights into November weather, you can visit Mystic weather in November.

September and December present markedly different weather patterns. September enjoys milder temperatures, with a minimum of 10°C (51°F) and an average high of 27°C (82°F), making it suitable for outdoor activities. In contrast, December brings a notable chill, with temperatures dropping to a minimum of -11°C (12°F) and an average of just 4°C (40°F). Additionally, while September experiences 101 mm (4.0 in) of precipitation over 9 days, December sees even more rain, totaling 141 mm (5.6 in) across 11 days. The humidity levels also rise slightly from September's 75% to December's 80%, contributing to the colder, wetter atmosphere. For more specific details on December conditions, you can check out the link: Mystic weather in December.

Compare Mystic's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Mystic

As summer gracefully transitions into autumn, September in Mystic presents a unique blend of mild temperatures and a touch of nostalgia. Unlike the sweltering heat of July and August, this month offers a more temperate climate, perfect for enjoying the stunning fall foliage. While rainfall is more frequent with about nine days of precipitation, the lush greenery thrives, enriching the landscape. The humidity levels also provide a comforting blanket, making it a delightful time to explore outdoor activities. For those keen to understand the full spectrum of Mystic's weather patterns, dive deeper into the details at Mystic Climate.