Last updated: February 24, 2025
Experience the captivating September weather in Mammoth Lakes, United States, where the average temperature settles at a pleasant 13°C (56°F). This month features maximum daytime highs reaching up to 30°C (86°F), while the evenings can cool down significantly, dipping to a brisk -6°C (22°F). Visitors can expect minimal rainfall, with only 9 mm (0.4 in) over the course of 2 days, paired with a comfortable humidity level of 42%. Enjoy the stunning natural beauty of Mammoth Lakes under a mix of warm days and crisp nights, perfect for outdoor adventures!
In September, Mammoth Lakes begins to transition from the warmth of summer to the crisp embrace of autumn. The temperatures show a notable range, with minimums dropping to -6°C (22°F), while average highs remain a comfortable 30°C (86°F), hinting at the lingering warmth of the season. This month balances cooler nights with pleasantly warm days, making it an ideal time for outdoor enthusiasts to explore the breathtaking landscapes. As the month progresses, you'll likely feel a subtle shift, as the cooling temperatures signal the impending arrival of autumn, inviting adventurers to relish in the stunning fall colors and changing scenery before winter settles in.
September in Mammoth Lakes marks a transition into the drier months, with precipitation dwindling to just 9 mm (0.4 in), accompanied by only 2 days of rainfall. This decline follows a summer of sparse showers, primarily seen in July and August, where totals hovered around 11 mm. As the region moves from the peak of summer, the consistent pattern emerges, showcasing significantly heavier rainfall in the earlier months of the year—particularly January and February, which both received over 130 mm. Overall, the data reveals a clear trend of decreasing precipitation as the seasons shift, with Mammoth Lakes experiencing the lightest rainfall of the year in September, hinting at the dry, crisp days of autumn ahead.
As summer transitions into autumn, September in Mammoth Lakes sees a noticeable uptick in humidity, reaching 42%. This marks a gradual shift from the very dry conditions of July and August, where humidity plunged to a mere 36% and 30%, respectively. The trend showcases the region’s typical seasonal rhythm, where the crisp mountain air begins to regain some moisture after the arid peak summer months. Despite this increase, September remains significantly less humid compared to the winter months, where levels soar to around 82% to 85% in January and February. This refreshing change may attract visitors looking to experience the stunning fall landscapes without the oppressive humidity.
As summer transitions to autumn, the UV Index in Mammoth Lakes begins to decline, yet September still maintains a very high UV Index of 10, requiring a careful approach to sun exposure with a burn time of just 15 minutes. This month marks a notable shift from the extreme levels witnessed in the peak summer months, indicating slightly lower, but still significant, sun intensity. Following September, the UV Index further decreases in October but remains in the very high category, still posing a risk for unprotected skin. As you enjoy the scenic beauty of Mammoth Lakes this September, remember to protect yourself against harmful UV rays. For more detailed information, check out the Mammoth Lakes UV Index.
UV Risk Categories
As September rolls in, Mammoth Lakes basks in 325 hours of glorious sunshine, marking a gentle transition from the vibrant summer months to the crispness of autumn. While this is a decline from the peak of July's 391 hours, it still outshines the earlier months of the year, showcasing an impressive increase from January's 171 hours. The sunshine hours in September are also notably higher than October's anticipated 294 hours, hinting at a lingering warmth in the air. This trend illustrates the area’s ability to hold onto sunny days even as the seasons shift, inviting both adventure seekers and leisure travelers to enjoy the stunning landscapes bathed in golden sunlight before winter's embrace.
As summer transitions into fall, Mammoth Lakes boasts an impressive 90% chance of sunny weather in September, making it one of the sunniest months of the year. This trend follows a dramatic rise in sunshine days, especially from April onward, where the likelihood increases from 72% in April to a peak in August at 91%. September maintains this momentum, providing visitors with ample opportunities to enjoy the stunning landscapes in bright, clear weather. Although October sees a drop to 65%, the lingering warmth of September is ideal for outdoor adventures, ensuring that the end of summer is celebrated under a vibrant blue sky.
As September arrives in Mammoth Lakes, the days begin to gradually shorten, offering about 12 hours of daylight. This marks a gentle decline from the longer days of summer, where sunlight peaked at 14 hours in June, July, and August. The transition is a reminder of the changing seasons, reflecting a sense of balance as nature prepares for the cooler months ahead. Following this pattern, the daylight will continue to recede in October and beyond, settling into a rhythm that alternates between longer days in spring and summer and shorter days through fall and winter. Each month brings its own unique charm, but September stands out as a beautiful blend of summer's lingering warmth and autumn's early whispers, inviting residents and visitors alike to savor the last warm rays of the year.
As the summer winds down in Mammoth Lakes, September brings a gentle breeze with an average wind speed of 2.0 m/s (4 mph), mirroring the early months of the year. This moderate airflow signals a transition from the slightly breezier summer months, where July peaked at 1.9 m/s (4 mph) and August at 2.1 m/s (5 mph). Interestingly, the wind tends to pick up again in October, averaging 2.3 m/s (5 mph), creating a sense of anticipation for the crisp autumn days ahead. Overall, the trend showcases a consistent, soothing wind pattern throughout the year, with September serving as a serene passage between the vibrant summer and the brisk fall.
The weather in Mammoth Lakes 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 Mammoth Lakes and find detailed weather information for every month.
September and January present starkly contrasting weather conditions. In September, temperatures can range from a chilly -6°C (22°F) at the lowest to a warm 30°C (86°F) at the highest, with an average of around 13°C (56°F) and only 9 mm (0.4 in) of precipitation over 2 days. This month enjoys a relatively low humidity level of 42%. In contrast, January is much colder, with temperatures dipping to a minimum of -23°C (-9°F), averaging -5°C (24°F), and peaking at just 10°C (51°F). Precipitation increases significantly during this month, totaling 130 mm (5.1 in) over 7 days, accompanied by a higher humidity of 82%. For more detailed information, you can refer to Mammoth Lakes weather in January.
September and February present striking contrasts in weather conditions. In September, temperatures range from a brisk -6°C (22°F) at night to a warm 30°C (86°F) during the day, with an average of 13°C (56°F) and only 9 mm (0.4 in) of precipitation over just 2 days, making it a relatively dry month with a humidity level of 42%. In contrast, February brings significantly colder temperatures, with minimums plunging to -21°C (-6°F) and daytime highs averaging just -4°C (25°F). February is also notably wetter, experiencing 129 mm (5.1 in) of precipitation across 9 days, accompanied by much higher humidity at 85%. For a more detailed look at February weather, you can visit Mammoth Lakes weather in February.
In comparing the weather between September and March, there are notable differences in temperature, precipitation, and humidity. September typically experiences milder temperatures, ranging from a minimum of -6°C (22°F) to a maximum of 30°C (86°F), with an average of 13°C (56°F). This month sees relatively low precipitation levels, averaging just 9 mm (0.4 in) over 2 days and maintaining a humidity level of 42%. In contrast, March presents much colder conditions, with temperatures ranging from a low of -20°C (-4°F) to a high of 15°C (58°F), averaging -2°C (28°F). The precipitation also significantly increases during this time, totaling 88 mm (3.5 in) over approximately 10 days, and humidity rises to 80%. For more detailed information about the March weather, you can check Mammoth Lakes weather in March.
The weather in September is notably warmer than in April, with average temperatures reaching 13°C (56°F) compared to just 2°C (36°F) in April. September can also see warmer days, with maximum temperatures hitting 30°C (86°F), whereas April’s highs only reach up to 18°C (65°F). Additionally, April tends to be wetter, receiving 49 mm (1.9 in) of precipitation over 6 days, while September enjoys a much drier climate with only 9 mm (0.4 in) of rain on just 2 days. The humidity levels are also higher in April at 72%, compared to 42% in September, contributing to a noticeably different feel in the air. For more details on April weather, check out Mammoth Lakes weather in April.
September and May present distinctly different weather patterns. In September, the temperature ranges from a chilly minimum of -6°C (22°F) to a pleasant maximum of 30°C (86°F), with an average of 13°C (56°F). The month sees relatively low precipitation, totaling just 9 mm (0.4 in) over 2 days, complemented by a humidity level of 42%. In contrast, May experiences a broader temperature range, with a minimum of -12°C (11°F) and a maximum of 25°C (78°F), averaging 6°C (43°F). This month is much wetter, receiving 40 mm (1.6 in) of precipitation across 9 days and higher humidity at 58%. For more detailed insights into the weather conditions during May, you can visit Mammoth Lakes weather in May.
In comparing the weather of September and June, both months display a range of temperatures, but September tends to be slightly warmer overall, with maximum temperatures reaching up to 30°C (86°F) compared to June's 29°C (84°F). The average temperatures are quite similar, with September averaging 13°C (56°F) and June at 14°C (57°F). Rainfall in June is slightly higher at 11 mm (0.4 in) over three days, while September experiences less precipitation at 9 mm (0.4 in) over only two days. Additionally, humidity levels are higher in June at 49%, compared to September's 42%. For more details on the June weather, you can check Mammoth Lakes weather in June.
When comparing the weather in September and July, September experiences a wider temperature range, with minimums dropping to -6°C (22°F) and maximums reaching up to 30°C (86°F). In contrast, July’s temperatures are generally milder, with minimums at 4°C (39°F) and maximums peaking at 31°C (87°F). Additionally, September enjoys significantly less precipitation, averaging only 9 mm (0.4 in) over 2 days, compared to July's 17 mm (0.7 in) over 4 days, although July is slightly more humid at 36% versus September's 42%. For more detailed insights about July weather specifics, you can visit Mammoth Lakes weather in July.
In September, the weather experiences a notable shift compared to August. While both months share a maximum temperature of 30°C (86°F), September showcases a broader temperature range with a minimum of -6°C (22°F) and an average of 13°C (56°F), making it feel significantly cooler, especially at night. Precipitation decreases slightly in September to 9 mm (0.4 in) over two days, contrasting with August's 11 mm (0.4 in) over three days. Notably, humidity levels rise in September to 42% compared to 30% in August, contributing to a different overall feel in the air. For a closer look at the weather specifics in August, check this link: Mammoth Lakes weather in August.
September generally experiences milder temperatures, with an average of 13°C (56°F) and a maximum reaching up to 30°C (86°F), while October sees a notable drop, averaging 7°C (44°F) and peaking at 24°C (75°F). Precipitation also changes as September has minimal rainfall of 9 mm (0.4 in) over just 2 days, whereas October brings more moisture with 23 mm (0.9 in) falling in a single day. Additionally, humidity levels increase from 42% in September to 59% in October, making the latter month feel more damp. For more detailed information, check out Mammoth Lakes weather in October.
In September, the weather is relatively mild, with temperatures ranging from a chilly -6°C (22°F) at night to a warm 30°C (86°F) during the day, and an average of 13°C (56°F). The month sees minimal precipitation, with only 9 mm (0.4 in) over just 2 days, and a comfortable humidity level of 42%. In contrast, November brings a significant drop in temperature, with nightly lows reaching -17°C (2°F) and daytime highs peaking at 19°C (66°F), resulting in an average of only 2°C (35°F). Additionally, November tends to be wetter, with 48 mm (1.9 in) of precipitation spread across 4 days and a much higher humidity of 78%. For more details about November weather, check out Mammoth Lakes weather in November.
In September, the weather is relatively mild with average temperatures around 13°C (56°F) and a maximum of 30°C (86°F), making it a pleasant time for outdoor activities. Precipitation is minimal, with only 9 mm (0.4 in) falling over just 2 days, and humidity levels are at a comfortable 42%. In contrast, December brings much colder temperatures, with averages dropping to -4°C (25°F) and a maximum of only 12°C (53°F). The month sees significantly more precipitation at 81 mm (3.2 in) over 7 days, along with higher humidity levels at 79%. For those interested in more detailed weather information, check out Mammoth Lakes weather in December.
September in Mammoth Lakes heralds a transition period as summer begins to wane, showcasing a refreshing blend of warm days and crisp nights. With maximum temperatures comfortably reaching 30°C (86°F) and cooler average figures, visitors can enjoy pleasant afternoons before the chill of the evening descends—often dipping to around -6°C (22°F). Rainfall is minimal, with just a couple of days experiencing a light sprinkle, making this month notably drier compared to the verdant spring and tumultuous winter months. Meanwhile, humidity is relatively low at 42%, enhancing the allure of outdoor activities against a backdrop of stunning fall foliage. For detailed insights on how September's weather compares with the rest of the year, visit Mammoth Lakes Climate.