Last updated: February 24, 2025
September in Hyannis, United States presents a delightful transition into autumn, characterized by pleasant temperatures and a moderate climate. The maximum temperature peaks at a comfortable 25°C (78°F), while the average hovers around 19°C (67°F), with nighttime lows reaching a refreshing 13°C (56°F). This month also witnesses 10 days of rain, totaling 118 mm (4.7 in) of precipitation, contributing to the region's vibrant fall foliage. With humidity levels around 75%, this period offers a unique blend of warm days and crisp evenings, making it an ideal time for outdoor activities and enjoying the scenic beauty of the Cape.
September in Hyannis, United States marks the gentle transition from summer to autumn, bringing a delightful shift in temperatures. With a minimum of 13°C (56°F) and a comfortable average of 19°C (67°F), the days remain pleasantly warm, peaking at a maximum of 25°C (78°F). This month stands out as the last hurrah of summer, inviting residents and visitors alike to enjoy outdoor activities under clear skies. As the warmth begins to recede, the month hints at the cooler days ahead, bridging the gap between the heat of summer and the crispness of fall. With these moderate temperatures, September offers a perfect blend of lingering summer vibes and the allure of autumn's approach.
September in Hyannis experiences a notable shift in precipitation, with an average accumulation of 118 mm (4.7 in) over approximately 10 rainy days. This marks a return to wetter conditions after the drier summer months, where July and August recorded their lowest precipitation levels of 83 mm (3.3 in) and 82 mm (3.2 in), respectively. As summer gives way to fall, the increase in rainfall sets the stage for October’s peak precipitation, which averages 175 mm (6.9 in). This trend highlights September as a transitional month, bridging the dry spell of summer with the wetter, more tumultuous weather typical of the autumn season in Hyannis.
In September, Hyannis experiences a notable shift in humidity, with levels settling at 75%, consistent with the gradual decline that began in mid-summer. This reduction continues a trend observed from the more oppressive summer months, where humidity hovered around 76% in both July and August. The fall season marks the beginning of a transition, as humidity levels maintain a balance, comparable to October's readings. While the early months of the year command higher humidity, often above 80%, September signals a welcome decrease, making it a more comfortable time to enjoy the outdoors in this charming coastal town. As autumn approaches, the air becomes crisper yet retains a hint of summer's lingering warmth.
As summer transitions to autumn, September in Hyannis, United States, sees a UV Index of 8, categorizing it as very high. This indicates that while it's not as intense as the peak summer months, sun exposure still poses a significant risk, with a burn time of just 15 minutes. Interestingly, the UV Index dips slightly from the 9 observed in August, reflecting a gradual shift toward cooler weather. Despite this decrease, it's vital for residents and visitors alike to remain vigilant about sun protection, ensuring they stay safe while enjoying the lingering warmth of early fall. For more detailed insights and updates, check out the Hyannis UV Index.
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As summer fades, September in Hyannis offers a delightful transition with 280 hours of sunshine, maintaining a lively glow while gently ushering in autumn. This month continues the trend of increasing daylight from the earlier months, showcasing a gradual peak over the sizzling summer, which saw July basking in a remarkable 346 hours. Although September experiences a dip compared to the sun-drenched days of July and August, it still enjoys more sunlight than the colder months to follow. This abundance of sunshine makes it an ideal time for outdoor adventures, family gatherings, and scenic strolls along the picturesque coastline before the chill of autumn sets in.
As September rolls into Hyannis, the chances of enjoying sunny weather brighten up considerably, with a 49% likelihood of sunshine. This marks an increase from the summer months, where the percentages hover around the mid-30s to low-40s. Interestingly, September stands out as a transition month, not only signaling the end of summer but also exhibiting one of the higher probabilities for sun, surpassed only by the sunnier months of March and November. As autumn approaches, residents and visitors alike can look forward to nearly half the days graced by sunshine, making it an inviting time to embrace the outdoors in this charming coastal town.
As summer fades into autumn, Hyannis experiences a gentle decline in daylight duration throughout September, averaging 12 hours of daylight. This month marks a significant transition, following the peak of 15 hours seen in June and the steady decrease in daylight hours that begins in August. The gradual shift from the bright, long days of summer to the shorter, more subdued days of fall becomes evident, as the sunlight decreases by an hour compared to August. This trend is part of a broader seasonal pattern in Hyannis, where daylight continues to wane into October, ultimately reaching a low of 9 hours by December. The rhythmic ebb and flow of daylight not only signify changing seasons but also offer a beautiful backdrop to the coastal charm of Hyannis.
As September rolls in, Hyannis experiences a refreshing gust of wind, with average speeds hovering around 5.9 m/s (13 mph). This marks a slight increase from the calm of August, reflecting a subtle shift as summer transitions into fall. Throughout the year, wind speeds tend to peak in the winter months, with January and February averaging 7.1 m/s and 7.2 m/s respectively, while the summer months show a gradual decline. Interestingly, late September brings about a slight revival in winds, reminiscent of the gentle breezes found in early spring. This pattern suggests that while summer enjoys the soft whispers of lighter winds, autumn begins to assert its presence with a brisker touch, inviting residents and visitors alike to enjoy the invigorating air of Hyannis.
The weather in Hyannis 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 Hyannis and find detailed weather information for every month.
September and January present stark contrasts in weather, reflecting the transition from late summer to winter. In September, temperatures are mild, with an average of 19°C (67°F) and maximums reaching 25°C (78°F), while January brings much colder conditions, averaging just 2°C (36°F) and peaking at 13°C (55°F). Precipitation is relatively similar in both months, with September experiencing about 118 mm (4.7 in) over 10 days, compared to January's 94 mm (3.7 in) also spread over 10 days. Additionally, humidity levels are notably higher in January at 84%, compared to September's 75%, which can contribute to a colder, more biting air feel. For a more detailed look at what to expect during the frigid month, check out Hyannis weather in January.
When comparing the weather in September and February, the differences are stark. September boasts a milder climate with average temperatures ranging from a minimum of 13°C (56°F) to a maximum of 25°C (78°F), alongside a pleasant average of 19°C (67°F). The month experiences about 118 mm (4.7 in) of precipitation over 10 days, combined with a humidity level of 75%, making it relatively comfortable. In contrast, February brings a much colder atmosphere, with temperatures dipping down to a minimum of -12°C (10°F) and reaching an average of just 2°C (36°F), peaking at 11°C (53°F). This month sees approximately 123 mm (4.8 in) of precipitation spread over 12 days, coupled with higher humidity at 84%, which can make the cold feel even more biting. For a more detailed look at February weather, check out Hyannis weather in February.
September and March present strikingly different weather conditions. In September, temperatures range from a minimum of 13°C (56°F) to a maximum of 25°C (78°F), creating a mild and pleasant atmosphere for outdoor activities. The average temperature sits at 19°C (67°F) with 118 mm (4.7 in) of rainfall spread over 10 days and a humidity level of 75%. In contrast, March experiences much colder weather with temperatures ranging from a minimum of -9°C (16°F) to a maximum of 13°C (56°F). The average temperature is only 3°C (38°F), and although the precipitation remains the same at 118 mm (4.7 in) over 10 days, March has a slightly higher humidity level of 82%. For a detailed look at the weather specifics in March, you can check out Hyannis weather in March.
When comparing the weather between September and April, there are notable differences in temperature and precipitation patterns. September typically enjoys milder temperatures, with a minimum of 13°C (56°F) and an average high reaching 25°C (78°F), making it a more pleasant month overall. In contrast, April's temperatures are significantly cooler, with a minimum of just 1°C (33°F) and an average high of 16°C (60°F).
Precipitation levels are also distinct; September sees about 118 mm (4.7 in) over approximately 10 days, while April has slightly higher rainfall at 137 mm (5.4 in) over 13 days, contributing to a wetter atmosphere. Both months experience comparable humidity levels, though April is slightly higher at 79% versus September's 75%. For a more detailed look at the weather patterns in April, you can visit Hyannis weather in April.
In comparing the weather of September and May, we can observe notable differences despite similar precipitation levels. September features a warmer climate with average temperatures ranging from a minimum of 13°C (56°F) to a maximum of 25°C (78°F), making it more conducive to outdoor activities. In contrast, May is cooler, with an average temperature between 5°C (41°F) and 21°C (70°F), as the season transitions from spring to summer. Both months experience a comparable amount of rainfall, with September receiving 118 mm over about 10 days, while May has slightly more precipitation at 119 mm over 12 days. Despite these similarities, the consistent humidity of 75% in both months adds a layer of comfort to the warmer September days. For a detailed look at weather patterns during this time, you can visit Hyannis weather in May.
When comparing the weather in September and June, we notice some distinct differences. September tends to be slightly warmer, with average temperatures reaching 19°C (67°F) compared to June's average of 17°C (63°F). The maximum temperatures are also a bit higher in September at 25°C (78°F), while June peaks at 24°C (76°F). However, September experiences more rainfall, with 118 mm (4.7 in) compared to June's 91 mm (3.6 in), both occurring over about 10 days. Humidity levels are relatively similar, with September at 75% and June slightly higher at 78%. For a more detailed look at June's weather, you can check Hyannis weather in June.
When comparing the weather in September to July, a noticeable change in temperature and precipitation patterns emerges. September experiences slightly cooler temperatures, with a minimum of 13°C (56°F) and a maximum of 25°C (78°F), while July boasts warmer conditions, ranging from a minimum of 16°C (61°F) to a maximum of 29°C (84°F). In terms of rainfall, September sees more precipitation with 118 mm (4.7 in) over 10 days, compared to July's 83 mm (3.3 in) spread over 9 days. Humidity levels remain fairly similar, with September at 75% and July slightly higher at 76%. For a closer look at July weather details, you can refer to Hyannis weather in July.
In comparing the weather patterns of August and September, we see a notable shift in temperature and precipitation. August generally boasts warmer temperatures, with minimums around 16°C (61°F) and maximums reaching 27°C (81°F), leading to an average of 22°C (72°F). In contrast, September sees cooler days, with a minimum of 13°C (56°F) and maximums peaking at 25°C (78°F), averaging 19°C (67°F). Additionally, September experiences more precipitation, totaling 118 mm (4.7 in) over 10 days, while August has a milder rainfall of 82 mm (3.2 in) over just 8 days. Both months exhibit high humidity levels, although September's average humidity slightly increases to 75% compared to August's 76%. For more specifics on August weather, visit Hyannis weather in August.
September's weather features warmer temperatures, with an average of 19°C (67°F) and maximums reaching 25°C (78°F). However, the month is characterized by frequent rainfall, totaling 118 mm (4.7 in) over 10 days. In contrast, October ushers in significantly cooler conditions, with an average temperature of 15°C (59°F) and minimums dropping to 4°C (39°F). Precipitation increases to 175 mm (6.9 in) over 12 days, while humidity remains consistent at 75%. For more details on what to expect, check out Hyannis weather in October.
September and November present contrasting weather patterns, with September offering milder temperatures ranging from a minimum of 13°C (56°F) to a maximum of 25°C (78°F). It experiences average humidity around 75% and receives significant rainfall of 118 mm (4.7 in) over 10 days. In contrast, November cools down considerably, with temperatures dropping to a minimum of -6°C (21°F) and an average of 9°C (48°F), peaking at 19°C (66°F). Although November sees a slightly lower total precipitation of 102 mm (4.0 in) across the same number of days, the humidity is slightly higher at 80%. For more detailed information on the weather in November, check Hyannis weather in November.
In September, the weather is mild, with average temperatures around 19°C (67°F) and maximums reaching up to 25°C (78°F). This month experiences moderate precipitation of 118 mm (4.7 in) over approximately 10 days, accompanied by a humidity level of 75%. In contrast, December sees a dramatic drop in temperatures, averaging only 4°C (40°F) and dipping as low as -12°C (11°F). The precipitation increases slightly to 136 mm (5.4 in) across 12 days, with humidity rising to 80%. For more details on December conditions, you can visit Hyannis weather in December.
As summer gives way to autumn, Hyannis experiences a notable shift in September weather, characterized by milder temperatures and increased humidity. With average highs around 19°C, the days are pleasantly warm yet a touch cooler than the peak summer months. This transition results in more frequent, albeit light, rainfall, with about 10 days seeing precipitation throughout the month, contributing to a moister atmosphere. While the warmth persists, the blend of comfortable days and refreshing evenings makes September a unique time to enjoy the charming beauty of Hyannis. For a detailed look at how Hyannis weather evolves throughout the year, explore Hyannis Climate.