September Weather in Big Sur, United States

Last updated: February 24, 2025

In September, Big Sur, United States, experiences a delightful transition into fall. With a maximum temperature reaching 33°C (91°F), the warm days are complemented by a comfortable average of 16°C (62°F) and a mild minimum of 9°C (49°F) at night. Notably, this month showcases remarkably low precipitation, recording just 4 mm (0.2 in) and boasting 0 rainy days. The humidity level hovers around 55%, creating a pleasant climate perfect for outdoor activities and exploration of the breathtaking coastal scenery.

September Temperature in Big Sur

In September, Big Sur welcomes mild temperatures that hint at the lingering warmth of summer. With minimums hovering around 9°C (49°F) and average temperatures reaching 16°C (62°F), visitors can expect comfortable days. What’s striking is the peak maximum of 33°C (91°F), showcasing the area’s ability to deliver a late-season heatwave that is both unusual and delightful. This month stands out as the transition to autumn begins, yet the warmth of summer still casts a spell over the region, inviting outdoor adventures against the backdrop of stunning coastal views. As the weather remains relatively pleasant, September provides the perfect opportunity to explore Big Sur’s natural beauty before the cooler months set in.

September Weather in Big Sur: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Big Sur, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec515050525458606161595551
Data source: Temperature data for Big Sur 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 Big Sur

September in Big Sur marks the tail end of a remarkably dry spell, with only 4 mm (0.2 inches) of precipitation recorded, and interestingly, no rainy days to speak of. This trend of minimal rainfall is characteristic of the late summer months, starting in June and extending through August, when the area typically experiences near-desert conditions. As autumn approaches, the precipitation begins to pick up gradually, foreshadowing a return to the wetter weather patterns seen earlier in the year. The stark contrast between the lush, rainy months of January through March, where totals peaked at 140 mm (5.5 inches), and the arid summer underscores the region's varied climate, making September a transitional month that bridges the dry season with the coming rains of fall.

September Precipitation Trends in Big Sur

The chart displays monthly precipitation patterns in Big Sur, 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.
JanFebMarAprMayJunJulAugSepOctNovDec140120110332321142143118
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Big Sur

In September, Big Sur experiences a subtle transition as humidity levels dip to 55%, marking one of the year's lowest points. This decline follows a pattern established throughout the summer months, where the humidity decreased steadily from 58% in July to 54% in August. As the warm summer gives way to the cooler autumn air, September's slight uptick in comfort is a refreshing change for visitors and locals alike. Interestingly, this month serves as a bridge before humidity begins to rise again in October, reaching 62%, hinting at the return of the cooler, wetter months ahead. Overall, September signals the tail end of dry summer weather and the onset of more variable conditions typical of coastal California.

September Average Humidity in Big Sur

This chart illustrates the average monthly humidity levels in Big Sur, 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%84%82%78%71%64%59%54%55%62%78%80%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Big Sur

As summer fades and September rolls in, Big Sur experiences a noticeable shift in its UV Index, dropping to 9, categorized as very high with a burn time of just 15 minutes. This trend reflects a gradual descent from the peak UV levels seen in the summer months of June through August, where the index reached a maximum of 12. As the sun remains potent even in early autumn, visitors should remain vigilant about sun protection, particularly during midday hours. This month serves as a reminder of the lingering intensity of the California sun, ensuring that outdoor enthusiasts plan accordingly to enjoy the breathtaking beauty while safeguarding their skin. For detailed information on UV exposure throughout the year, visit Big Sur UV Index.

Maximum UV Index Levels in Big Sur for September

The chart shows the monthly maximum UV Index (UVI) for Big Sur 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.
JanFebMarAprMayJunJulAugSepOctNovDec4589111211119753
Data source: Big Sur 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 Big Sur

As summer gently fades into autumn, September in Big Sur continues to bask in a generous 314 hours of sunshine, reflecting a robust trend of warmth and light that peaks during the summer months. Following a spectacular July with 388 hours, September's sunshine notably remains abundant, though it signals the onset of cooler days. This slight decline is characteristic of the seasonal shift, as the region transitions from the high summer radiance to the more tempered sunlight of fall. While the month brings fewer hours than its immediate predecessors, it still stands firmly above the winter months, showcasing Big Sur's enduring beauty and inviting atmosphere, perfect for those seeking to relish the tranquility before the winter chill sets in.

Monthly Sunshine Duration in Big Sur: September Highlighted

The September sunshine duration represents the total number of hours Big Sur 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.
JanFebMarAprMayJunJulAugSepOctNovDec163h220h264h302h359h376h388h357h314h289h235h209h
Data source: Big Sur September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Big Sur During September

As summer transitions into fall, September in Big Sur maintains a high likelihood of sunny weather, boasting a 79% chance of sun. This month continues the trend established over the summer, where sun-filled days peak in August at 80%. While the sunny probabilities begin to taper off in the following months, September's generous sunshine offers a fantastic opportunity for outdoor adventures before the cooler October sets in, which drops to 64%. With September's warm, inviting atmosphere, it’s a prime time to bask in the beauty of Big Sur's stunning coastline.

Percentage of Sunny Days in September in Big Sur

The chart illustrates the percentage of sunny days in Big Sur 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 Big Sur experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec47%57%51%59%73%73%70%80%79%64%59%45%
Data source: Big Sur September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Big Sur in September

As summer fades into autumn, September in Big Sur, United States, brings a delightful transition in daylight duration. With about 12 hours of sunlight, this month marks the gradual decline from the peak of summer, where July bathed the coast in a generous 14 hours. Following August's slight decrease, September's daylight still offers ample opportunities to bask in the stunning coastal scenery, yet signals the approach of shorter days ahead. This pattern reflects the natural rhythms of the seasons, reminding us that while the warm glow of summer lingers, nature is quietly readying itself for the cozy embrace of fall.

Average Daylight Hours in Big Sur for September

The chart illustrates the variation in daylight duration in Big Sur throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec9h 59m10h 52m11h 59m13h 8m14h 6m14h 34m14h 18m13h 27m12h 21m11h 12m10h 13m9h 43m
Data source: Big Sur daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Big Sur

As summer fades into fall, September in Big Sur presents a remarkable transition in wind patterns. The average wind speed drops to a gentle 3.2 m/s (7 mph), mirroring the tranquility of this coastal paradise as it gently shifts from the bustling summer months. Earlier in the year, winds picked up momentum, particularly in May with an average of 4.9 m/s (11 mph), but have steadily decreased since. The shift towards calmer winds continues from August, reflecting a serene atmosphere that invites visitors to bask in the breathtaking landscapes without the distractions of stronger breezes. As autumn approaches, the cool, mild air offers a perfect backdrop for enjoying the stunning vistas that Big Sur is renowned for.

Average September Wind Speed in Big Sur

The chart displays monthly wind speed patterns in Big Sur, 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.
JanFebMarAprMayJunJulAugSepOctNovDec4.04.33.94.44.94.33.53.23.2 m/s3.73.53.9
Data source: Big Sur September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Big Sur Compares to Other Months

The weather in Big Sur 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 Sur and find detailed weather information for every month.

September and January present striking contrasts in weather conditions. September boasts warmer temperatures, with a minimum of 9°C (49°F) and a maximum reaching up to 33°C (91°F), while enjoying very little precipitation at just 4 mm (0.2 in) and low humidity of 55%. In stark comparison, January experiences cooler temperatures, where the minimum drops to 3°C (38°F) and the maximum peaks at 20°C (69°F). This month is also characterized by much higher precipitation, accumulating 140 mm (5.5 in) over about 8 days and humidity levels rising to 82%. For a more detailed look at January weather, you can check out Big Sur weather in January.

September and February exhibit vastly different weather conditions. In September, temperatures can range from a mild 9°C (49°F) at night to a sweltering 33°C (91°F) during the day, with an average of 16°C (62°F). Precipitation is minimal, with only about 4 mm (0.2 in) and virtually no rainy days, resulting in a moderate humidity level of 55%. In contrast, February experiences cooler temperatures, with a minimum of 2°C (36°F) and a maximum of 23°C (74°F), averaging just 10°C (51°F). This month sees significantly higher precipitation of 120 mm (4.7 in) spread over 9 days, accompanied by increased humidity at 84%. For more insights into February weather, you can explore Big Sur weather in February.

In September, the weather tends to be much warmer, with temperatures ranging from a minimum of 9°C (49°F) to a maximum of 33°C (91°F), and an average of 16°C (62°F). The month experiences very little precipitation, with only 4 mm (0.2 in) on just a single day, resulting in a comfortable humidity level of 55%. In contrast, March is notably cooler, with temperatures dropping to a minimum of 4°C (39°F) and reaching a maximum of 21°C (70°F), averaging at 10°C (51°F). This spring month sees significantly higher precipitation at 109 mm (4.3 in) over 13 days, accompanied by increased humidity at 82%. For more details about the weather in March, you can refer to Big Sur weather in March.

When comparing the weather in September and April, notable differences emerge in temperature and precipitation. September boasts a wider temperature range, with minimums around 9°C (49°F) and maximums peaking at 33°C (91°F), resulting in an average of 16°C (62°F). This month enjoys relatively dry conditions with only 4 mm (0.2 in) of precipitation and low humidity at 55%. In contrast, April sees cooler temperatures, with minimums dipping to 5°C (41°F) and maximums reaching 25°C (78°F), averaging at 11°C (53°F). Additionally, April is far wetter, receiving 33 mm (1.3 in) of precipitation over 5 days and exhibiting higher humidity at 78%. For more detailed insights, you can check Big Sur weather in April.

In September, the weather tends to be warmer with average temperatures reaching around 16°C (62°F) and a maximum of 33°C (91°F), while May offers cooler conditions with an average of 12°C (54°F) and a peak of only 24°C (75°F). September boasts minimal precipitation with an average of just 4 mm (0.2 in) and no rainy days, contrasting sharply with May’s wetter climate, which sees about 23 mm (0.9 in) spread over three days. Additionally, September’s humidity is lower at 55%, making it feel more comfortable compared to May's higher humidity level of 71%. For those interested in a deeper look at May’s weather specifics, check out Big Sur weather in May.

In comparing the weather of September and June, September tends to be warmer overall, with average temperatures peaking at 16°C (62°F) and reaching a maximum of 33°C (91°F). In contrast, June features cooler conditions, with an average temperature of 14°C (58°F) and a maximum of 27°C (81°F). Both months experience minimal precipitation, with September receiving slightly more at 4 mm (0.2 in) compared to June's 2 mm (0.1 in), and neither month sees any rainy days. Humidity levels are also noteworthy, with September at 55% and June higher at 64%. For those interested in the specifics of weather patterns, Big Sur weather in June provides detailed insights.

In comparing the weather between September and July, September tends to showcase a broader range of temperatures, with a minimum of 9°C (49°F), an average of 16°C (62°F), and a maximum soaring to 33°C (91°F). In contrast, July's temperatures are generally milder, featuring a similar minimum of 9°C (49°F) but with an average of 15°C (60°F) and a maximum of just 24°C (75°F). Both months experienced negligible precipitation, with September receiving only 4 mm (0.2 in) and July only 1 mm (0.0 in), resulting in dry conditions. Humidity levels are relatively comparable, with September at 55% and July slightly higher at 58%. For more detailed information on July weather, you can visit Big Sur weather in July.

September and August exhibit notable differences in temperature, though their averages remain similar. In September, temperatures range from a minimum of 9°C (49°F) to a maximum of 33°C (91°F), showcasing more extreme highs compared to August, which has a temperature range of 11°C (51°F) to 28°C (82°F). Both months experience minimal precipitation, with September accumulating only 4 mm and August slightly lower at 1 mm, making for dry conditions in each period. Humidity levels are comparable, standing at 55% in September and slightly lower at 54% in August. For more specific insights into August weather, you can refer to Big Sur weather in August.

In September, the weather is characterized by warmer temperatures, with a minimum of 9°C (49°F) and an average of 16°C (62°F). The month sees a high of 33°C (91°F) and very little precipitation, only 4 mm (0.2 in) spread over no rainy days, resulting in a humidity level of 55%. In contrast, October experiences a slight drop in temperature, with a minimum of 7°C (45°F) and an average of 15°C (59°F). The maximum temperature also decreases to 31°C (88°F), and there's a notable increase in precipitation to 21 mm (0.8 in) over one day, leading to a higher humidity of 62%. For more detailed information on October weather, check out Big Sur weather in October.

September and November present contrasting weather patterns. In September, temperatures range from a comfortable minimum of 9°C (49°F) to a high of 33°C (91°F), with an average of 16°C (62°F). The month is relatively dry, seeing just 4 mm (0.2 in) of precipitation and maintaining a humidity level of 55%. In stark contrast, November experiences cooler temperatures, with a minimum of 4°C (40°F) and a maximum of 24°C (75°F), averaging at 13°C (55°F). This month also witnesses significantly more rainfall, accumulating 43 mm (1.7 in) over 5 rainy days, and higher humidity at 78%. For further insights into November weather specifics, check out Big Sur weather in November.

September and December exhibit distinct differences in weather patterns. In September, temperatures range from a mild 9°C (49°F) at night to a warm 33°C (91°F) during the day, with low humidity at 55% and minimal precipitation. In contrast, December sees cooler temperatures, with averages dropping to a minimum of 4°C (40°F) and a maximum of 23°C (74°F). The month is characterized by significantly higher precipitation, totaling 118 mm (4.6 in) over 9 days, along with increased humidity at 80%. For more detailed information, you can check Big Sur weather in December.

Compare Big Sur's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Big Sur

As summer transitions into fall, September in Big Sur showcases a mild and pleasant climate, setting it apart from the hotter months of July and August. The average temperature remains comfortable, allowing for outdoor adventures against the backdrop of stunning coastal landscapes. With precipitation virtually absent—only 4 mm recorded—this month boasts clear skies and a refreshing yet moderate humidity level of 55%. This unique blend of warm days and cool evenings makes September an ideal time for visitors seeking a break from the summer heat while enjoying the natural beauty of this iconic region. For more insights on the shifting seasons, check out the full details at Big Sur Climate.