September Weather in Yosemite Valley, United States

Last updated: February 24, 2025

Explore the enchanting September weather in Yosemite Valley, where nature's beauty shines under a gentle sun. With maximum temperatures soaring to 28°C (83°F), visitors can relish warm days perfect for outdoor activities. As the average temperature settles at a comfortable 13°C (55°F), it's an ideal time for hiking and sightseeing. Nights can bring a refreshing chill, dipping as low as -8°C (18°F). Although precipitation is modest at 17 mm (0.7 in) over just 4 days, the humidity remains a pleasant 42%, ensuring the valley’s radiant landscapes remain vibrant and inviting. Experience September's unique charm in this breathtaking destination!

September Temperature in Yosemite Valley

In September, Yosemite Valley transitions to cooler temperatures as summer gives way to autumn. The month welcomes a refreshing shift, with minimum temperatures dropping to -8°C (18°F) and maximums reaching a comfortable 28°C (83°F). This significant range allows adventurers to experience the valley in a more temperate climate, perfect for hiking and sightseeing. The average temperature of 13°C (55°F) strikes a pleasant balance, making early fall an ideal time to visit before the chill of winter sets in. This period showcases the stunning natural beauty of Yosemite, with fewer crowds and a vibrant landscape that invites exploration.

September Weather in Yosemite Valley: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Yosemite Valley, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec272729364255636255443627
Data source: Temperature data for Yosemite Valley generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Yosemite Valley

In Yosemite Valley, September marks a continuation of the dry summer season, with precipitation averaging just 17 mm (0.7 in) over four days—a sharp contrast to the rain-soaked months of winter and spring. This minimal rainfall is reminiscent of August, indicating a consistent trend of decreasing moisture as the region transitions into fall. Typically characterized by clear skies and mild temperatures, September provides an ideal backdrop for outdoor exploration in the stunning granite landscapes of Yosemite. As the month progresses and the leaves begin to change, visitors can enjoy the serene beauty of the valley, witnessing nature in a state of quiet transformation, even amid the typically dry conditions.

September Precipitation Trends in Yosemite Valley

The chart displays monthly precipitation patterns in Yosemite Valley, 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.
JanFebMarAprMayJunJulAugSepOctNovDec22722620910268202417174398160
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Yosemite Valley

As summer fades into fall, September humidity in Yosemite Valley begins to rise, registering at 42% after the peak dryness of August, which saw a low of just 30%. This transitional month hints at the approaching autumn, as humidity levels show a gradual increase from the dry spell experienced in the heart of summer. The trend reflects a notable contrast from earlier months: while January through April showcase higher humidity levels ranging from 72% to 85%, the late summer months plummet, hitting a minimum in July. With October around the corner, humidity further increases, setting the stage for the lush, refreshing conditions of fall that follow. As Yosemite's iconic landscape prepares for seasonal change, the shifting humidity patterns enhance the beauty and experience of this stunning natural wonder.

September Average Humidity in Yosemite Valley

This chart illustrates the average monthly humidity levels in Yosemite Valley, 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.
JanFebMarAprMayJunJulAugSepOctNovDec82%85%80%72%58%49%36%30%42%59%78%79%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Yosemite Valley

As September arrives in Yosemite Valley, the UV Index remains significant, reading 10 and categorized as very high, which calls for heightened sun safety awareness. This month marks a slight drop from the summer months, peaking at 12 in June and July, but still presents a challenge for outdoor enthusiasts, with a burn time of approximately 15 minutes for unprotected skin. The trend shows a gradual decline in UV intensity as fall approaches, starting from the extreme levels witnessed earlier in the season. It’s a reminder for visitors to balance their love for the breathtaking landscape with mindful sun protection. To learn more about UV levels and stay safe, check out Yosemite Valley UV Index.

Maximum UV Index Levels in Yosemite Valley for September

The chart shows the monthly maximum UV Index (UVI) for Yosemite Valley 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.
JanFebMarAprMayJunJulAugSepOctNovDec469111212121110754
Data source: Yosemite Valley 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 Yosemite Valley

As September unfolds in Yosemite Valley, visitors can bask in a delightful average of 323 sunshine hours, gracefully tapering from the peak summer days. This month marks a transition, as the valley's vibrant greenery begins to shift towards autumn hues. The sunlight, while still abundant, reflects a gentle decline from the summer’s zenith of 392 hours in July. September's golden rays invite outdoor adventures against a backdrop of stunning fall foliage, capturing the essence of seasonal change. With sunshine hours gradually decreasing towards October, the valley offers a serene and picturesque escape, perfect for hiking, photography, and embracing nature’s beauty. The trend of diminishing light reminds us to relish every sunny moment before winter's embrace.

Monthly Sunshine Duration in Yosemite Valley: September Highlighted

The September sunshine duration represents the total number of hours Yosemite Valley 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.
JanFebMarAprMayJunJulAugSepOctNovDec170h224h273h318h366h388h392h364h323h293h241h210h
Data source: Yosemite Valley September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Yosemite Valley During September

September in Yosemite Valley is a delightful time for sun-seekers, boasting a remarkable 89% chance of sunny weather. This month is part of a trend that showcases steadily increasing sunshine as summer approaches its peak; after starting the year with only a 44% likelihood in January, the chances for clear skies leap dramatically by August. As the days transition into fall, September still holds on to much of that summer warmth and brightness, making it an ideal time for outdoor adventures. With sunlight nearly guaranteed, visitors can fully immerse themselves in the breathtaking beauty of Yosemite’s landscapes.

Percentage of Sunny Days in September in Yosemite Valley

The chart illustrates the percentage of sunny days in Yosemite Valley 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 Yosemite Valley experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec44%58%55%69%81%81%73%92%89%62%65%40%
Data source: Yosemite Valley September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Yosemite Valley in September

As the summer wanes in Yosemite Valley, September heralds a subtle yet noticeable shift in daylight duration. With 12 hours of daylight, this month marks a gentle decline from the peak 14 hours enjoyed in June through August. The longer days of summer gradually give way to a cozy autumn ambiance, foreshadowing the shorter days ahead. This transition fosters a unique atmosphere in the valley, where the rich hues of early fall become illuminated in the soft light, encouraging visitors to revel in the stunning landscapes with plenty of daylight to explore. Amidst this change, the rhythm of nature subtly reminds us of summer's end and autumn's embrace.

Average Daylight Hours in Yosemite Valley for September

The chart illustrates the variation in daylight duration in Yosemite Valley throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 52m10h 48m11h 59m13h 12m14h 13m14h 43m14h 26m13h 32m12h 22m11h 9m10h 6m9h 34m
Data source: Yosemite Valley daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Yosemite Valley

In Yosemite Valley, September marks a continuation of the gentle breezes that have characterized the summer months, with an average wind speed of 2.0 m/s (5 mph). This relatively calm atmosphere reflects a trend throughout the year, where wind speeds show little variability, hovering around the 2.1 m/s (5 mph) mark from January through June. As summer transitions to fall, there's a slight easing of winds, particularly in July, which dips to 1.8 m/s (4 mph), before stabilizing again in September. This rhythmic pattern not only enhances the serene beauty of the valley but also invites visitors to fully embrace its tranquil charm, making it an inviting time for exploration and reflection amidst the stunning natural landscape.

Average September Wind Speed in Yosemite Valley

The chart displays monthly wind speed patterns in Yosemite Valley, 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.
JanFebMarAprMayJunJulAugSepOctNovDec2.12.12.12.02.02.11.82.02.0 m/s2.01.82.2
Data source: Yosemite Valley September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Yosemite Valley Compares to Other Months

The weather in Yosemite Valley 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 Yosemite Valley and find detailed weather information for every month.

In September, weather in Yosemite Valley typically features a milder temperature range, with minimums around -8°C (18°F) and maximums reaching up to 28°C (83°F). The average temperature is a comfortable 13°C (55°F), accompanied by relatively low precipitation of 17 mm (0.7 in) over about four days, and humidity levels around 42%. In contrast, January brings a stark change, with minimum temperatures dropping to -18°C (0°F) and a chilly average of -3°C (27°F). The maximum temperature is also significantly lower, capping at 11°C (51°F). January is much wetter, receiving 227 mm (9.0 in) of precipitation across about nine days, leading to higher humidity levels at 82%. For more detailed information, you can refer to Yosemite Valley weather in January.

September and February present starkly contrasting weather conditions. In September, temperatures range from a chilly -8°C (18°F) at night, up to a pleasant average of 13°C (55°F), with maximum highs reaching 28°C (83°F). The month experiences relatively light precipitation, averaging just 17 mm (0.7 in) over approximately 4 days, with a humidity level of 42%. In comparison, February is significantly colder, with minimum temperatures plunging to -21°C (-5°F) and an average of -3°C (27°F). It also sees much more precipitation, totaling 226 mm (8.9 in) across about 11 days, accompanied by high humidity at 85%. For more detailed insights into February weather specifically, you can check out Yosemite Valley weather in February.

When comparing the weather in September and March, it's clear that both months present distinct conditions. September typically enjoys milder temperatures, ranging from a chilly minimum of -8°C (18°F) to an average of 13°C (55°F) and a maximum of 28°C (83°F). With only 17 mm (0.7 in) of precipitation spread across about 4 days, the humidity is relatively low at 42%. In contrast, March is much colder, with temperatures plummeting to a minimum of -17°C (1°F) and an average of -2°C (29°F), peaking at only 13°C (56°F). This month is notably wetter, receiving 209 mm (8.2 in) of precipitation over 13 days, and the humidity is significantly higher at 80%. For more details on March weather in Yosemite Valley, visit Yosemite Valley weather in March.

Comparing the weather between September and April reveals distinct differences in temperature and precipitation. September typically enjoys a milder climate, with average temperatures ranging from a minimum of -8°C (18°F) to a maximum of 28°C (83°F), along with low humidity at 42% and only 17 mm (0.7 in) of precipitation over about 4 days. In contrast, April experiences cooler temperatures, with a minimum of -18°C (0°F) and a maximum of 16°C (60°F), higher humidity at 72%, and significantly more precipitation totaling 102 mm (4.0 in) over approximately 8 days. For a closer look at April weather conditions in Yosemite Valley, you can visit Yosemite Valley weather in April.

When comparing the weather in September and May, several differences stand out. September boasts a more varied temperature range with minimums dipping to -8°C (18°F) and maximums reaching 28°C (83°F), while the average temperature sits at a comfortable 13°C (55°F). In contrast, May experiences lower maximums at 24°C (75°F) but a colder minimum of -13°C (9°F), resulting in a cooler average of 6°C (43°F). Additionally, precipitation in May is significantly higher at 68 mm (2.7 in) over 11 days, compared to just 17 mm (0.7 in) over 4 days in September. This leads to a higher humidity level in May, recorded at 58%, compared to the drier September humidity of 42%. For more detailed insights, you can check the Yosemite Valley weather in May.

In comparing the weather of September and June, we find that both months have similar average temperatures, with September averaging 13°C (55°F). However, September tends to experience slightly warmer highs, reaching up to 28°C (83°F), compared to June's maximum of 27°C (81°F). The precipitation levels are fairly close as well, with September receiving 17 mm (0.7 in) over 4 days and June slightly wetter at 20 mm (0.8 in) over 5 days. Notably, June also has higher humidity at 49%, while September's humidity is lower at 42%. For more details, you can check out the Yosemite Valley weather in June.

In September, the weather shows a broader temperature range, with minimums dipping to -8°C (18°F) while averaging 13°C (55°F) and peaking at 28°C (83°F). The month experiences a lower total precipitation of 17 mm (0.7 in) over 4 days, coupled with a humidity level of 42%. In contrast, July maintains milder temperatures, with a minimum of 3°C (37°F), an average of 17°C (63°F), and a maximum reaching 29°C (85°F). July sees slightly higher precipitation at 24 mm (0.9 in) over 6 days, and has lower humidity at 36%. For more detailed insights, you can explore the Yosemite Valley weather in July.

In comparing the weather for September and August, we see notable differences in temperature and humidity. September experiences a broader temperature range, with a minimum of -8°C (18°F) and an average of 13°C (55°F), while August has a milder minimum of 4°C (39°F) and an average of 16°C (62°F). Both months receive similar precipitation amounts of 17 mm (0.7 in), but August has slightly more rainy days, totaling five compared to September's four. Additionally, September offers a higher humidity level at 42%, compared to August’s 30%, making it feel different despite the similar rainfall. For more details about the weather in August, you can check Yosemite Valley weather in August.

In September, temperatures in the region often ranged from a minimum of -8°C (18°F) to a maximum of 28°C (83°F), with an average of 13°C (55°F). The month saw relatively low precipitation, totaling 17 mm (0.7 in) over 4 days, and the humidity hovered around 42%. In contrast, October brings cooler weather with temperatures dropping to a minimum of -10°C (15°F) and a maximum of 24°C (75°F), averaging just 7°C (44°F). Additionally, October experiences an increase in precipitation, amounting to 43 mm (1.7 in) but over only 3 days, and the humidity rises to 59%. For more detailed information, you can check out Yosemite Valley weather in October.

September and November exhibit stark contrasts in weather. In September, temperatures range from a minimum of -8°C (18°F) to a maximum of 28°C (83°F), with an average of 13°C (55°F). This month experiences relatively low precipitation, averaging just 17 mm (0.7 in) over four days and maintaining a comfortable humidity level of 42%. In contrast, November sees a significant drop in temperatures, with a minimum of -20°C (-4°F), an average of 2°C (36°F), and a maximum of 18°C (65°F). This month is much wetter, with 98 mm (3.9 in) of precipitation over six days, coupled with higher humidity at 78%. These differences highlight the transition from the mild late summer of September to the colder, wetter conditions typical of November. For more detailed information, refer to Yosemite Valley weather in November.

Comparing September and December weather reveals significant variations in temperature and precipitation. September enjoys milder temperatures with a minimum of -8°C (18°F) and an average of 13°C (55°F), while December sees much colder conditions, with lows dropping to -17°C (1°F) and an average of -3°C (27°F). Additionally, September experiences relatively low precipitation at 17 mm (0.7 in) over just 4 days, whereas December is much wetter, with total precipitation reaching 160 mm (6.3 in) spread over 10 days. Humidity also increases considerably, rising from 42% in September to 79% in December, contributing to a much chillier feel during the winter months. For a more detailed look at December weather, you can check Yosemite Valley weather in December.

Compare Yosemite Valley's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Yosemite Valley

September in Yosemite Valley marks a transition into milder weather, characterized by gentle warmth during the day and cooler nights, which is a refreshing change from the height of summer. Visitors can expect relatively low humidity and infrequent rain, allowing for enjoyable outdoor activities. While the daytime temperatures can still reach pleasantly warm levels, the early mornings and nights see a noticeable drop, making it essential to prepare for temperature fluctuations. As the month progresses, the beauty of autumn begins to unfold, offering a stunning backdrop for all who venture into the valley. For more detailed insights into the seasonal variations, check out Yosemite Valley Climate.