Last updated: February 24, 2025
In September, Fort Collins, United States, experiences a captivating mix of temperatures, with a maximum reaching 37°C (99°F) and a cozy average of 19°C (66°F). As the month progresses, the nights bring a refreshing drop, dipping to a minimum of -1°C (31°F). Rainfall is modest, with 26 mm (1.0 in) over 4 days, contributing to a humidity level of 63%, providing a crisp and invigorating atmosphere. This transitional period from summer to autumn showcases the area's diverse weather, making it an intriguing month for both locals and visitors alike.
In September, Fort Collins experiences a delightful transition into fall, marked by mild temperatures that provide a welcome reprieve from the summer heat. The average temperature hovers around 19°C (66°F), typically ranging from a minimum of -1°C (31°F) at night to a balmy maximum of 37°C (99°F) during the day. This month is notable for its significant cooling trend compared to the sweltering summer months, reflecting a gradual shift as the region approaches winter. As the days shorten and the air turns crisp, September offers a perfect backdrop for outdoor activities, making it an ideal time to enjoy the stunning fall foliage that envelops the area.
In September, Fort Collins experiences a moderate shift in precipitation, receiving around 26 mm (1.0 in) of rain over just 4 days. This marks a notable decrease from the earlier summer months, especially considering May’s peak of 116 mm (4.6 in). As the city transitions from the warmth of summer into the cooler embrace of fall, these rainfall patterns become vital for replenishing moisture levels in preparation for winter. September's relatively calm and dry conditions hint at the city’s gradual drying trend, a characteristic signature of late summer and early autumn in this vibrant region.
In Fort Collins, the month of September continues the trend of moderate humidity that starts to emerge during the late summer. With humidity levels at 63%, September mirrors the slightly lower conditions of July and August, signaling a transition as the cooler autumn months approach. This period is part of a broader trend where humidity gradually decreases from the peak levels of winter, which hover around 84% to 85% in January and February. As the seasons change, the air becomes crisper, yet the lingering warmth of late summer ensures that the humidity remains comfortable for outdoor activities, making September a delightful month in this vibrant city.
As September rolls into Fort Collins, the UV Index reflects a transition to cooler months, yet it remains in the very high category at a UV Index of 9, with a burn time of just 15 minutes. This marks a slight decrease from the extreme levels seen during the peak summer months but signals that sun protection is still crucial. Overall, the trend throughout the year shows a gradual shift from moderate levels in January to extreme exposure in the summer, before tapering off in the fall. As the days grow shorter, residents should stay vigilant about UV rays, especially in early September. For more detailed information, visit Fort Collins UV Index.
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As summer gracefully transitions into autumn, September in Fort Collins continues to bask in a generous 306 hours of sunshine. This month reflects a notable decline from the summer's peak—July and June shining with 382 and 374 hours, respectively—but still showcases a comfortable abundance of sunlight compared to the cooler months ahead. April and May set the stage for this radiant season, with 300 and 327 hours respectively, paving the way for September’s golden warmth. As the days shorten, Fort Collins invites residents and visitors alike to enjoy the gentle kiss of the sun before it recedes into the brisk air of October. This rhythmic ebb and flow of sunlight not only marks the changing seasons but also highlights the beauty of Fort Collins’ weather patterns throughout the year.
As September rolls into Fort Collins, the chances of basking in sunny weather rise to an impressive 69%, marking it as one of the sunniest months of the year. This trend reflects a steady increase in sunshine from the earlier months, with August peaking at 66%. The summer months, particularly July and June, see the sun shining brightly, but it's September that truly cements its place as a delightful transition into autumn. As temperatures begin to cool, the joyful embrace of late summer sunshine makes this month perfect for outdoor activities and enjoying the splendor of nature.
As summer fades into autumn, September in Fort Collins, United States, witnesses a gentle decline in daylight, averaging 12 hours. This month reflects a transition from the sun-drenched days of July and August, where daylight peaked at 14 and 13 hours, respectively. Following this noticeable peak, September marks the beginning of shorter days, leading into October's 11 hours. The gradual decrease in daylight signifies nature's preparation for the cooler months ahead, creating a captivating interplay of light and shadow that characterizes early fall in this vibrant community.
In September, the average wind speed in Fort Collins mirrors the gentle breezes of the preceding summer months, maintaining a consistent 2.4 m/s (5 mph). This stability contrasts with the subtle fluctuations seen earlier in the year, where April brought slightly brisker winds at 2.7 m/s (6 mph). As the warm days of summer transition to the crisp air of fall, September's breezes embody a calm and soothing quality, creating the perfect backdrop for outdoor activities. The annual wind patterns reveal a tendency for the wind to be milder, creating a tranquil atmosphere that invites both locals and visitors to enjoy the picturesque scenery as the leaves begin to change.
The weather in Fort Collins 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 Fort Collins and find detailed weather information for every month.
September and January present stark contrasts in weather in Fort Collins. September enjoys milder temperatures, with averages around 19°C (66°F) and maximums soaring up to 37°C (99°F), accompanied by relatively low precipitation of 26 mm (1.0 in) over just four days. In contrast, January is dominated by cold, with average temperatures plummeting to -1°C (30°F) and lows dipping as low as -26°C (-14°F). Though it sees slightly less precipitation at 17 mm (0.7 in) over the same number of days, the humidity is notably higher at 84%, contributing to the chill in the air. For more detailed information, check out Fort Collins weather in January.
September and February present strikingly different weather patterns. In September, temperatures range from a chilly minimum of -1°C (31°F) to a sweltering maximum of 37°C (99°F), with an average of 19°C (66°F). The month experiences relatively low precipitation at 26 mm (1.0 in) over just 4 days, coupled with a humidity level of 63%. In contrast, February is much colder, with temperatures dipping as low as -25°C (-13°F) and peaking at 24°C (75°F), resulting in an average of -2°C (29°F). Although February sees slightly less precipitation at 23 mm (0.9 in), it occurs over more days (6), and humidity is higher at 85%. For more detailed insights into February weather, visit Fort Collins weather in February.
September and March exhibit a striking contrast in weather patterns. In September, temperatures are warmer, ranging from a minimum of -1°C (31°F) to a maximum of 37°C (99°F), with an average of 19°C (66°F) and relatively low precipitation at 26 mm (1.0 in) over just 4 days. The humidity sits at 63%, offering a pleasant warmth as summer transitions into fall. In contrast, March experiences much colder temperatures, with a minimum of -21°C (-5°F) and a maximum of 26°C (79°F), averaging only 4°C (40°F). The month also brings increased precipitation, totaling 53 mm (2.1 in) across 9 days, along with higher humidity levels at 75%. This indicates a shift towards wetter and chillier conditions as winter wanes. For a more detailed look at March weather patterns, you can check Fort Collins weather in March.
When comparing the weather in September and April, significant differences emerge in temperature and precipitation patterns. September boasts a wider temperature range, with minimums around -1°C (31°F) and maximums reaching up to 37°C (99°F), averaging a comfortable 19°C (66°F). In contrast, April features colder conditions, with minimum temperatures dropping to -13°C (9°F) and maximums capping at 29°C (85°F), resulting in an average of only 8°C (47°F). Moreover, September experiences less precipitation, totaling 26 mm (1.0 in) over just 4 days, while April receives a higher precipitation of 53 mm (2.1 in) across 10 days. This results in a slight increase in humidity levels in April at 67%, compared to September's 63%. For a more detailed look at these conditions, check out Fort Collins weather in April.
September and May exhibit distinctly different weather patterns. In September, temperatures can range from a chilly -1°C (31°F) to a sweltering max of 37°C (99°F), with an average of 19°C (66°F). The month experiences relatively low precipitation, totaling 26 mm (1.0 in) over just 4 days, and maintains a humidity level of 63%.
In contrast, May presents cooler temperatures, with a minimum of -3°C (27°F) and an average of 13°C (56°F), reaching a comfortable maximum of 31°C (88°F). However, May is notably wetter, receiving 116 mm (4.6 in) of rainfall over 14 days and exhibiting slightly higher humidity at 67%. For those interested in more details, check out Fort Collins weather in May.
In comparing the weather of September and June, we notice some intriguing differences and similarities. September experiences a wider range of temperatures, with minimums dropping to -1°C (31°F) and maximums peaking at 37°C (99°F), while the average temperature is slightly lower at 19°C (66°F). In contrast, June starts at a higher minimum of 5°C (41°F) and has a similar maximum of 38°C (100°F), with an average temperature of 20°C (68°F). However, June also sees more precipitation, totaling 40 mm (1.6 in) over approximately 8 days, compared to September's 26 mm (1.0 in) over just 4 days. Humidity levels are somewhat comparable, with June at 68% and September at 63%. For a more detailed look at June's weather patterns, you can refer to this link: Fort Collins weather in June.
In comparing the weather between September and July, we observe some notable differences. September experiences a wider temperature range with minimums dropping as low as -1°C (31°F) and maximums reaching up to 37°C (99°F). In contrast, July has a milder minimum temperature of 9°C (49°F) and a similar maximum that matches September's peak. Both months have comparable average temperatures, with September averaging 19°C (66°F) and July at 23°C (74°F). Precipitation is slightly less in September, totaling 26 mm (1.0 in) over 4 days, compared to July's 30 mm (1.2 in) over 6 days, resulting in a similar humidity level of around 63% for September and 62% for July. For more detailed information on July weather, you can check out Fort Collins weather in July.
In comparing the weather between August and September, September exhibits a greater temperature range, with minimums dropping to -1°C (31°F) and maximums reaching up to 37°C (99°F). The average temperature in September is 19°C (66°F), which is cooler than August's average of 22°C (72°F). Additionally, while both months have high humidity levels of 63%, September sees a slight decrease in precipitation with 26 mm (1.0 in) over 4 days, compared to August's 37 mm (1.5 in) over 6 days. This shift in weather patterns marks a transition toward the cooler conditions typical of autumn. For more details about August's weather, you can visit Fort Collins weather in August.
In comparing the weather between September and October, there is a noticeable shift in temperatures and precipitation patterns. September showcases a broader temperature range with a minimum of -1°C (31°F) and a maximum of 37°C (99°F), averaging at a comfortable 19°C (66°F). The month experiences relatively low precipitation of 26 mm (1.0 in) over just 4 days and maintains a humidity level of 63%.
In contrast, October brings cooler temperatures, with a minimum dropping to -16°C (3°F) and an average of 9°C (49°F), peaking at a maximum of 29°C (84°F). The month sees increased precipitation at 36 mm (1.4 in) spread over 7 days, alongside a rise in humidity to 72%. Such changes mark a transition toward the chill of late autumn. For a detailed look at October weather specifically, you can visit Fort Collins weather in October.
In September, the weather boasts a much warmer average temperature of 19°C (66°F), with maximum highs reaching up to 37°C (99°F) and a relatively comfortable humidity level of 63%. Precipitation is minimal at 26 mm (1.0 in) over 4 days. In contrast, November experiences a significant drop in temperatures, with an average of just 4°C (40°F), and night temperatures plummeting to a chilly -15°C (6°F). Although November sees slightly less precipitation at 21 mm (0.8 in) over 5 days, the humidity increases to 79%, adding to the overall cool and damp atmosphere. For more details on November weather, you can visit Fort Collins weather in November.
In September, the weather is significantly warmer, with average temperatures around 19°C (66°F) and highs reaching up to 37°C (99°F). The month experiences relatively low precipitation, averaging 26 mm (1.0 in) over four days, accompanied by a comfortable humidity level of 63%. In contrast, December brings much colder conditions, with average temperatures dropping to just 1°C (33°F) and minimums plummeting to -16°C (3°F). Although precipitation is lower at 16 mm (0.6 in) over three days, the humidity rises to 85%, creating a stark difference in the overall feel of the weather. For more detailed information, you can visit Fort Collins weather in December.
As summer gives way to autumn, September in Fort Collins brings a delightful shift in weather. The days are pleasantly warm, often accentuated by crisp mornings and cooler evenings, setting it apart from the sweltering heat of July and August. With a notable decrease in humidity, the air feels refreshing, making outdoor activities highly enjoyable. Occasional rain showers, albeit minimal, provide a gentle reminder of the changing seasons. This month, characterized by its moderate temperatures and welcoming atmosphere, offers a perfect opportunity to embrace the beauty of Fort Collins. For more insights on the seasonal transition, check out Fort Collins Climate.