Last updated: February 24, 2025
In September, Big Sky, United States, experiences a dynamic range of weather, with maximum temperatures reaching a pleasant 28°C (83°F) and average daily temperatures hovering around a crisp 9°C (48°F). The month greets adventurers and locals alike with a significant chill, as minimum temperatures can dip to a brisk -9°C (16°F). Amidst this temperature variation, precipitation plays a notable role, totaling 59 mm (2.3 in) over approximately 8 days, contributing to a humidity level of 67%. This blend of conditions creates a beautiful tapestry of early autumn in the mountains, making it an ideal time for outdoor activities and enjoying the stunning landscapes.
September in Big Sky, United States, marks a subtle shift toward autumn, as temperatures begin to cool down from the summer warmth. With a minimum of -9°C (16°F) and a maximum reaching 28°C (83°F), this month showcases a comfortable average of 9°C (48°F), representing a transitional period that balances lingering summer days with the onset of chilly evenings. The decreasing temperatures reflect a broader trend, as the region moves from the warm highs enjoyed in July and August, both of which recorded maximums of 29°C (85°F). This gradual change not only invites the stunning hues of fall foliage but also encourages outdoor adventure enthusiasts to savor the crisp air before winter arrives.
In September, Big Sky experiences a moderate increase in precipitation, with 59 mm (2.3 in) falling over just 8 days, marking a transition toward the wetter months ahead. This amount is slightly higher than the previous month, August, which recorded 56 mm (2.2 in), despite having more days of rainfall. As summer gives way to autumn, the precipitation trend hints at the seasonal shift, with the town preparing for the increases in moisture typical of October and beyond. Overall, September offers a balance of sunny days and refreshing rains, setting the stage for the vibrant fall colors in the surrounding landscapes.
As summer transitions into fall, September in Big Sky presents a noticeable shift in humidity levels, dropping to 67%. This decrease continues a downward trend observed from the peak of 93% in January to the more moderate figures seen throughout the summer months, culminating in 69% humidity in August. With each passing month, humidity has gradually receded, making September feel noticeably drier and more comfortable. However, this dry spell is short-lived, as the humidity begins to climb again in October, ultimately returning to the higher levels typical of winter. This rhythm of fluctuating humidity highlights Big Sky’s diverse climate, transitioning from the dampness of winter to the refreshing crispness of early fall.
As summer fades in Big Sky, September ushers in a very high UV Index of 9, indicating that while the sun's intensity diminishes slightly from the peak of summer, it still poses a risk for unprotected skin. The burn time in this month is approximately 15 minutes, a shift from the extreme levels seen during the height of June and July, which boasted indices of 11 and 12. Despite this reduction, outdoor enthusiasts should remain vigilant and protect themselves, as the exposure category remains significant. Understanding these trends underscores the importance of sun safety as we transition into fall. For more detailed information, check out the Big Sky UV Index.
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As the warm embrace of summer gives way to early autumn, September in Big Sky unfolds with 284 hours of sunshine, a delightful transition from the sun-drenched July and June that boast impressive totals of 392 and 356 hours, respectively. This month reflects a gentle decline in sunlight, signaling the onset of the cozy fall season while still offering ample opportunities for enjoying the great outdoors. August's lingering warmth with 349 hours brings September its golden glow, inviting visitors to relish the tail end of summer explorations. As daylight recedes, the crisp air begins to hint at the impending beauty of autumn foliage, making September a perfect time to experience Big Sky's stunning landscapes bathed in the soft light of early fall.
September in Big Sky, United States, marks a delightful transition into autumn, bringing with it a promising 72% chance of sun. As summer wraps up, residents and visitors alike can relish the lingering warmth and brightness, making it one of the sunniest months of the year. This notable increase in sunny days follows the peak summer months of June and July, where the sun shines brightly 73% and 62% of the time, respectively. As we shift into fall, the likelihood of sunny weather remains high, echoing the trend seen from the vibrant summer, and allowing for plenty of opportunities to enjoy the great outdoors before the cooler months set in. With such favorable conditions, September stands out as an ideal time to explore the stunning landscapes and outdoor activities that Big Sky has to offer.
As September rolls into Big Sky, United States, daylight begins to wane, offering a gentle transition from the vibrant summer months. With an average of 12 hours of daylight, this month still enjoys a healthy amount of sunshine, yet it marks a noticeable decline from July and August, which bask in 15 and 13 hours, respectively. The trend is clear: as summer's warmth fades, daylight gradually shrinks, setting the stage for the cozy embrace of autumn. Just days away from October's shorter days, September captures a moment of balance, blending the lingering brightness of summer with the anticipation of the seasonal shift.
As summer gracefully transitions into autumn, September in Big Sky showcases a gentle breeze with an average wind speed of 2.3 m/s (5 mph). This subtle increase from the calmer summer months reflects a trend of returning stability after July's lowest wind speeds at 1.9 m/s (4 mph). With the changing season, September maintains a consistent airflow, drawing on influences that hint at the upcoming crispness of fall. As the year progresses, the wind speed gradually picks up, peaking in December at 3.1 m/s (7 mph), but for now, September offers a delightful balance—inviting outdoor activities while hinting at nature's impending transformation.
The weather in Big Sky 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 Big Sky and find detailed weather information for every month.
In September, temperatures vary significantly, with a minimum of -9°C (16°F) and a pleasant average of 9°C (48°F), peaking at a warm 28°C (83°F). This month experiences moderate precipitation of 59 mm (2.3 in) over about 8 days and maintains a humidity level of 67%. In stark contrast, January presents a much harsher climate with lower temperatures, where the minimum dips to -28°C (-19°F) and the average stands at a chilly -9°C (16°F), only reaching a maximum of 3°C (37°F). Although January sees less precipitation at 42 mm (1.6 in) across 11 days, the humidity rises significantly to 93%. For more detailed insights on the January weather, check out Big Sky weather in January.
When comparing the weather in September and February, notable contrasts emerge. September experiences milder temperatures with a minimum of -9°C (16°F) and an average of 9°C (48°F), reaching a maximum of 28°C (83°F). Humidity is relatively moderate at 67%, and precipitation is limited to 59 mm (2.3 in) over about 8 days. In stark contrast, February sees significantly harsher conditions, with temperatures plummeting to a minimum of -33°C (-27°F) and averaging -9°C (15°F), with a maximum of only 5°C (42°F). The month is characterized by higher humidity at 92% and increased precipitation, totaling 82 mm (3.2 in) over 17 days. For more detailed insights on February weather, visit Big Sky weather in February.
September and March display contrasting weather patterns. In September, temperatures range from a minimum of -9°C (16°F) to a maximum of 28°C (83°F), averaging a mild 9°C (48°F) with relatively lower humidity at 67%. The month experiences around 59 mm (2.3 in) of precipitation over approximately 8 days. In contrast, March presents a harsher climate, with temperatures dipping as low as -27°C (-17°F) and peaking at 12°C (53°F), averaging -4°C (26°F). This month is wetter, accumulating 65 mm (2.6 in) of precipitation over 13 days, while the humidity is notably higher at 89%. For more detailed insights into the weather during March, check out Big Sky weather in March.
Comparing the weather in September and April reveals distinct differences in temperature and precipitation patterns. In September, temperatures range from a chilly minimum of -9°C (16°F) to a warm maximum of 28°C (83°F), with an average of 9°C (48°F) and relatively moderate humidity at 67%. In contrast, April is notably colder, with minimum temperatures dropping to -20°C (-4°F) and a maximum of only 15°C (59°F), resulting in an average temperature of -1°C (30°F). April also sees higher precipitation levels, totaling 90 mm (3.6 in) over 16 days, compared to September's 59 mm (2.3 in) across just 8 days. Additionally, April experiences increased humidity levels at 83%, making it feel even colder. For more details on the specific climate conditions, you can check out Big Sky weather in April.
September generally offers a broader temperature range compared to May, with minimums of -9°C (16°F) and a maximum of 28°C (83°F), leading to an average temperature of 9°C (48°F). In contrast, May tends to be cooler overall, with temperatures ranging from -11°C (13°F) to a maximum of 21°C (70°F), resulting in an average of 3°C (38°F). Additionally, September experiences less precipitation, totaling 59 mm (2.3 in) over 8 days, compared to May's 89 mm (3.5 in) spread over 19 days. However, May also sees higher humidity levels at 79%, compared to September's 67%. For more detailed information on the weather in Big Sky during May, you can check Big Sky weather in May.
When comparing the weather in September to that of June, notable differences emerge. September typically experiences a broader temperature range, with minimums reaching -9°C (16°F) and maximums climbing to 28°C (83°F), resulting in an average temperature of 9°C (48°F). In contrast, June's temperatures are slightly more moderate, with a minimum of -8°C (17°F) and a maximum of 27°C (81°F), yielding an average of 10°C (51°F). Additionally, June is characterized by higher precipitation levels, with 102 mm (4.0 in) recorded over 16 days, compared to September's 59 mm (2.3 in) over just 8 days. This results in a comparatively higher humidity level in June at 76%, versus September's 67%. For more detailed information, you can check Big Sky weather in June.
In comparing the weather of September and July, September exhibits a broader temperature range, with average temps around 9°C (48°F) and a maximum of 28°C (83°F), while July boasts a slightly warmer average of 15°C (60°F) with a peak of 29°C (85°F). Both months experience significant humidity, though September's average humidity is at 67%, slightly lower than July's 74%. Precipitation is more frequent in July, with rain on 12 days and a total of 44 mm (1.7 in), compared to September's 8 rainy days and 59 mm (2.3 in) of rain. For more details on July weather, visit Big Sky weather in July.
In comparing the weather between September and August, September tends to be slightly cooler, with an average temperature of 9°C (48°F) compared to August's warmer average of 14°C (58°F). The maximum temperatures are similar, peaking at 28°C (83°F) in September and 29°C (85°F) in August. Precipitation is fairly consistent, with September receiving 59 mm (2.3 in) over 8 days and August having 56 mm (2.2 in) over 11 days. Humidity levels are also quite close, with September at 67% and August at 69%. For more specific details about August weather, you can visit Big Sky weather in August.
In September, the weather shows a wide temperature range, with minimums around -9°C (16°F) and maximums reaching up to 28°C (83°F), averaging at 9°C (48°F). Precipitation is moderate, with 59 mm (2.3 in) over 8 days and a humidity level of 67%. In contrast, October brings a significant drop in temperatures, with lows plummeting to -30°C (-22°F) and a cool average of -1°C (31°F). The month also experiences increased precipitation, totaling 77 mm (3.0 in) over 14 days and slightly higher humidity at 72%. For more detailed information about the weather during this month, check out Big Sky weather in October.
September and November present distinctly different weather patterns. In September, temperatures range from a mild minimum of -9°C (16°F) to a warm maximum of 28°C (83°F), with an average of 9°C (48°F). The month receives around 59 mm (2.3 in) of precipitation over 8 days and has a humidity level of 67%. In contrast, November sees a significant drop in temperatures, with a minimum of -22°C (-7°F) and an average of -5°C (23°F), peaking at just 12°C (54°F). This month also experiences slightly higher precipitation at 61 mm (2.4 in) but for more days, totaling 13, and humidity increases considerably to 89%. For more detailed insights on November weather, check out Big Sky weather in November.
September and December present striking contrasts in weather. In September, temperatures range from a chilly -9°C (16°F) at night to a pleasant 28°C (83°F) during the day, with an average of 9°C (48°F). This month sees about 59 mm (2.3 in) of precipitation over 8 days, accompanied by a relative humidity of 67%. In stark contrast, December plunges temperatures much lower, with nighttime lows reaching -27°C (-15°F) and daily highs maxing out at only 7°C (44°F), resulting in an average temperature of -9°C (16°F). Precipitation for December is slightly less, at 49 mm (1.9 in) over 13 days, but the humidity rises significantly to 94%. For more details about winter weather conditions, check out Big Sky weather in December.
As September unfolds in Big Sky, the weather presents a fascinating transition from the warmth of summer to the coolness of autumn. With daytime temperatures dipping significantly and the nights embracing a chill, this month showcases vivid contrasts that make it truly unique. The average temperature hovers around a brisk 9°C, while occasional warm spells can push highs up to 28°C, allowing for enchanting golden hour hiking before the crisp air sets in. As the days shorten, the dampness increases, with nearly 8 days of precipitation and an overall humidity of 67%, signaling the onset of autumnal changes. This evolving climate invites nature lovers to experience the beautiful transition in a serene mountain backdrop. Learn more about what to expect throughout the year at Big Sky Climate.