September Weather in San Diego, Mexico

Last updated: April 22, 2025

September in San Diego, Mexico, features a warm climate with a maximum temperature reaching 33°C (92°F) and an average of 24°C (75°F), providing a pleasant backdrop for outdoor activities. The month experiences a minimum temperature of 16°C (61°F), ensuring comfort during cooler evenings. However, be prepared for the rainy season, as the region receives 156 mm (6.2 in) of precipitation over 19 days, contributing to a humidity level of 82%. Whether you're exploring the coastline or savoring local cuisine, September offers a uniquely vibrant atmosphere amidst the fluctuating weather.

September Temperature in San Diego

As September rolls in, the temperatures in San Diego, Mexico begin to transition into the mild warmth of autumn. With a minimum of 16°C (61°F) and an average of 24°C (75°F), the days remain comfortably warm, reaching a maximum of 33°C (92°F). This slight dip in high temperatures from the sweltering end of summer provides a refreshing reprieve, setting the stage for pleasant outdoor activities. The shift towards cooler evenings enhances the overall experience, encouraging both locals and visitors to savor the charming coastal atmosphere. Overall, September showcases a harmonious blend of warmth and comfort, making it an inviting time to explore San Diego's vibrant offerings.

September Weather in San Diego: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in San Diego, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec707274787975767675747270
Data source: Temperature data for San Diego 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 San Diego

September in San Diego, Mexico, marks a significant peak in precipitation, as the region experiences 156 mm (6.2 in) of rain over 19 days. This surge follows a summer filled with increasing rainfall, highlighted by August’s 91 mm (3.6 in), indicating a distinct transition into the wetter months. September’s downpours are a stark contrast to the drier beginning of the year, where January and February recorded minimal rainfall of 8 mm (0.3 in) and 5 mm (0.2 in) respectively. The trend reveals that late summer and early fall are pivotal for replenishing local water sources, setting the tone for the drier months ahead. As the year progresses, one can expect a gradual tapering off in precipitation, with notable drops in October and beyond, ensuring the cycle of rainfall plays a crucial role in the region’s climate.

September Precipitation Trends in San Diego

The chart displays monthly precipitation patterns in San Diego, 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.
JanFebMarAprMayJunJulAugSepOctNovDec85511881834292156134318
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in San Diego

As summer transitions into fall, September in San Diego reveals a notable trend in humidity, maintaining a steady 82%, consistent with the levels observed in August. This peak humidity reflects the warm, tropical conditions characteristic of late summer, as the coastal region continues to experience the effects of lingering moisture from the Pacific. Following this high, the humidity gently rises to 83% in October, suggesting an ongoing embrace of coastal moisture that prepares the city for the approaching rainy season. Throughout the rest of the year, humidity fluctuates between the mid-50s and low 80s, showcasing San Diego's unique blend of coastal charm and atmospheric consistency.

September Average Humidity in San Diego

This chart illustrates the average monthly humidity levels in San Diego, 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.
JanFebMarAprMayJunJulAugSepOctNovDec76%68%59%57%65%66%75%82%82%83%80%76%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in San Diego

As we move into September, San Diego, Mexico continues to experience an extreme UV Index of 14, reflecting a consistent trend from the previous summer months. This high level of UV exposure, which translates to a quick burn time of just 10 minutes, underscores the importance of sun protection during this period. Throughout the year, particularly from February to July, the UV Index remains impressively high, often reaching extreme levels of 13 or more, peaking at 15 in both April and July. After September, the UV Index appears to decrease slightly in October but remains at an extreme level. For anyone spending time outdoors, staying informed is crucial; more details can be found at San Diego UV Index.

Maximum UV Index Levels in San Diego for September

The chart shows the monthly maximum UV Index (UVI) for San Diego 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.
JanFebMarAprMayJunJulAugSepOctNovDec10131415141415141413109
Data source: San Diego 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 San Diego

As summer transitions into fall, San Diego's September showcases a delightful balance of sunshine with an impressive 293 hours of sunshine—just slightly below the summer peak. This month follows a trend of abundant sun, particularly evident in July, which boasts the highest total of 329 hours. While the late summer months of August and September maintain similar levels of sunshine, the slight dip reflects the gradual shift toward cooler autumn days. With consistently high numbers throughout the year, from February's 287 hours to July's peak, San Diego remains a sun lover's paradise, making it an ideal destination for those seeking warmth and vibrant outdoor experiences even as the seasons begin to change.

Monthly Sunshine Duration in San Diego: September Highlighted

The September sunshine duration represents the total number of hours San Diego 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.
JanFebMarAprMayJunJulAugSepOctNovDec252h287h324h314h314h278h329h318h293h295h304h316h
Data source: San Diego September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in San Diego During September

In September, San Diego, Mexico, experiences relatively low chances of sunny weather, with only a 23% likelihood of sun. As the summer months wane, the trend shows a significant decline in sunshine, peaking in February and March at 79% and 77% respectively, before dropping sharply as the rainy season approaches. The transition from May’s 35% to September’s 23% reflects a consistent decrease in sunny days, making this month one of the cloudier periods of the year. For those planning a trip, it’s wise to take this into account, as September offers fewer sunlit hours compared to the earlier months.

Percentage of Sunny Days in September in San Diego

The chart illustrates the percentage of sunny days in San Diego 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 San Diego experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec54%79%77%55%35%18%26%21%23%42%54%71%
Data source: San Diego September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in San Diego in September

In San Diego, Mexico, September stands out as a month where daylight stabilizes at 12 hours, consistent with the longer days of summer that stretch from June through August. This period marks a gentle transition from the sunniest days to the shorter daylight hours of autumn. As we move from late spring into autumn, the duration of daylight in San Diego reflects a gradual change, beginning with 11 hours in the early months of the year and peaking at 13 hours during June, before returning to 12 hours in both September and August. This trend highlights the region's relatively stable daylight duration, creating perfect opportunities for outdoor activities throughout the summer and early autumn months. Following September, daylight begins to wane again in October, bringing us back to the 11 hours of light seen in the winter months.

Average Daylight Hours in San Diego for September

The chart illustrates the variation in daylight duration in San Diego throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec11h 17m11h 37m12h 2m12h 29m12h 51m13h 2m12h 56m12h 37m12h 11m11h 44m11h 22m11h 11m
Data source: San Diego daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in San Diego

As September rolls in, San Diego, Mexico experiences a gentle sigh of a breeze, boasting an average wind speed of just 1.2 m/s (3 mph). This marks one of the calmest months of the year, as the winds tend to taper off after the playful gusts of summer. Following a brief peak in the spring and the steady winds of July, September's lighter breezes hint at the transition into the autumn months. While the summer typically drapes the area in milder currents, the arrival of fall begins to showcase a gradual resurgence in wind speeds, setting the stage for October’s modest uptick. As the seasons change, so too does the character of the winds, offering a serene backdrop for those enjoying the coastal beauty of San Diego.

Average September Wind Speed in San Diego

The chart displays monthly wind speed patterns in San Diego, 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.
JanFebMarAprMayJunJulAugSepOctNovDec2.32.32.62.21.81.22.31.61.2 m/s1.52.42.2
Data source: San Diego September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in San Diego Compares to Other Months

The weather in San Diego 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 San Diego and find detailed weather information for every month.

September and January present quite contrasting weather experiences. In September, temperatures range from a mild 16°C (61°F) to a warm 33°C (92°F), with an average of 24°C (75°F). This month is also characterized by higher humidity at 82% and significant rainfall, accumulating 156 mm (6.2 in) over 19 days. In stark contrast, January features cooler temperatures, with a minimum of 10°C (50°F) and a maximum of 33°C (93°F), but the average temperature is a comfortable 21°C (70°F). Additionally, January boasts much drier conditions, with only 8 mm (0.3 in) of precipitation over just one day and lower humidity at 76%. For more details, you can refer to San Diego weather in January.

In September, the weather is generally warmer and more humid, with average temperatures ranging from a minimum of 16°C (61°F) to a maximum of 33°C (92°F). This month also sees significant rainfall, with 156 mm (6.2 in) accumulating over 19 days, resulting in a humidity level of 82%.

In contrast, February experiences milder temperatures, with a minimum of 10°C (50°F) and a maximum of 35°C (96°F). The precipitation is drastically lower at just 5 mm (0.2 in), occurring over only 1 day, which contributes to a more comfortable humidity level at 68%. For a more detailed look at February weather, you can visit San Diego weather in February.

In September, the weather is generally warmer and more humid, with average temperatures ranging from a minimum of 16°C (61°F) to a maximum of 33°C (92°F). This month also experiences significant rainfall, with an average precipitation of 156 mm (6.2 in) over approximately 19 days, resulting in a high humidity level of 82%. In contrast, March tends to be milder and drier, featuring temperatures that range from a minimum of 11°C (53°F) to a maximum of 36°C (96°F). Notably, March has minimal precipitation, averaging only 5 mm (0.2 in) over just 1 day and a lower humidity of 59%. For more insights, check out San Diego weather in March.

Comparing the weather in September and April reveals distinct differences in temperature, precipitation, and humidity. September sees a broader temperature range, with a minimum of 16°C (61°F) and a maximum of 33°C (92°F), along with significant rainfall—156 mm over 19 days, leading to a high humidity of 82%. In contrast, April experiences milder temperatures, with a minimum of 14°C (57°F) and a peak of 37°C (99°F) but very little precipitation at just 11 mm over 2 days, resulting in a lower humidity of 57%. For more detailed insights, you can check San Diego weather in April.

September and May offer contrasting weather patterns. In September, temperatures range from a minimum of 16°C (61°F) to a maximum of 33°C (92°F), with an average of 24°C (75°F). This month sees significant precipitation, totaling 156 mm (6.2 in) over 19 days, and high humidity at 82%. In comparison, May tends to be warmer, with temperatures fluctuating from a minimum of 17°C (62°F) to a high of 37°C (99°F) and an average of 26°C (79°F). The precipitation in May is notably less, at 88 mm (3.5 in) over 14 days, and the humidity is lower at 65%. For more details on weather patterns, especially in May, check San Diego weather in May.

In comparing the weather between September and June, both months exhibit similar average temperatures, hovering around 24°C (75°F), but their extremes differ slightly. June tends to be warmer, featuring maximum temperatures that can reach up to 35°C (95°F) compared to September's maximum of 33°C (92°F). Additionally, June experiences slightly higher precipitation, with 183 mm (7.2 in) falling over 20 days, while September has 156 mm (6.2 in) across 19 days. Humidity levels are also notable, with September being more humid at 82%, compared to June's relatively lower humidity of 66%. For more insights about June weather, you can visit San Diego weather in June.

September weather exhibits a more varied temperature range compared to July, with a minimum of 16°C (61°F) and a maximum of 33°C (92°F). In contrast, July tends to be slightly hotter, peaking at 35°C (95°F), although both months share the same minimum temperature. Additionally, September is significantly wetter, receiving 156 mm (6.2 in) of precipitation over 19 days, while July sees much less rainfall at only 42 mm (1.6 in) across 6 days. The humidity is also higher in September at 82%, compared to 75% in July, making September feel more humid and damp. For a detailed look at July's climate, check out San Diego weather in July.

In comparing the weather between September and August, September tends to be slightly cooler, featuring a minimum temperature of 16°C (61°F) and an average of 24°C (75°F), while August sees higher temperatures with a minimum of 16°C (61°F) and an average of 25°C (76°F). August records higher maximum temperatures reaching up to 36°C (97°F) compared to September's peak of 33°C (92°F). Additionally, September experiences significantly more rainfall, with 156 mm (6.2 in) of precipitation over 19 days, versus August's 91 mm (3.6 in) over 14 days. Both months maintain a consistent humidity level of 82%. For more insights, you can check San Diego weather in August.

In September, the weather features a pleasant average temperature of 24°C (75°F), with maximums reaching 33°C (92°F). The month also sees considerable rainfall, totaling 156 mm (6.2 in) across 19 days, contributing to a humidity level of 82%. In comparison, October experiences slightly cooler average temperatures at 23°C (74°F), although maximums can still reach up to 34°C (93°F). Rainfall decreases to 134 mm (5.3 in) over 15 days, and humidity remains marginally higher at 83%. For more details, you can check San Diego weather in October.

In comparing the weather between September and November, September is characterized by warmer temperatures, with an average of 24°C (75°F) and maximums reaching up to 33°C (92°F). It also experiences higher precipitation, totaling 156 mm (6.2 in) over 19 days, resulting in a humid environment with an average humidity of 82%. In contrast, November sees slightly cooler temperatures, with an average of 22°C (72°F) and minimums dropping to 13°C (55°F). The month is also significantly drier, with only 31 mm (1.2 in) of precipitation across just 5 days, and humidity decreases slightly to 80%. For more details, you can visit San Diego weather in November.

In September, the weather is characterized by warm temperatures ranging from a minimum of 16°C (61°F) to a maximum of 33°C (92°F), with an average around 24°C (75°F). This month also sees significant rainfall, with about 156 mm (6.2 in) spread over 19 days, leading to high humidity levels of 82%. In contrast, December brings cooler conditions, with a minimum temperature of 10°C (51°F) and a maximum of 32°C (90°F), averaging 21°C (71°F). Notably, December experiences much less precipitation, only 8 mm (0.3 in) over just 2 days, resulting in lower humidity at 76%. For more details about weather patterns during this time, check San Diego weather in December.

Compare San Diego's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in San Diego

As September unfolds in San Diego, the weather presents a unique blend of warmth and moisture, contrasting sharply with the drier summer months. With average temperatures hovering around a pleasant 24°C (75°F), the city enjoys sunny days, yet the increased humidity and frequent precipitation—spanning 19 days—remind residents that summer's grip is loosening. This transition period fosters a vibrant atmosphere, making September an exceptional time to experience the city’s beauty before the cooler fall days arrive. For more insights into what to expect throughout the year, visit San Diego Climate.