Last updated: February 24, 2025
In San Marcos, United States, September presents a dynamic weather experience characterized by a maximum temperature reaching 38°C (100°F) and an average of 26°C (79°F), providing warm days ideal for outdoor activities. However, the month also brings cooler moments, with nighttime temperatures dropping to a minimum of 11°C (53°F). With 112 mm (4.4 in) of precipitation spread over 11 days, residents and visitors can expect occasional rain, contributing to the region's moderate 65% humidity. This blend of warmth, rainfall, and humidity defines September's unique climate, inviting both adventure and a touch of relaxation.
As summer transitions to fall in San Marcos, September showcases a delightful blend of warmth and comfort. The temperatures drop from the peak summer highs, with average temperatures settling at a pleasant 26°C (79°F). While the minimum temperature hovers around 11°C (53°F), the days can still reach a notable 38°C (100°F), reflecting a lingering summer vibe. This month marks a shift from the relentless heat of July and August, where temperatures soar above 40°C (104°F), to a more moderate warmth that invites outdoor activities and leisurely evenings. Overall, September serves as a refreshing prelude to the cooler months ahead, providing the perfect backdrop for enjoying the beautiful Texan landscapes.
In September, San Marcos experiences a slight uptick in precipitation, recording 112 mm (4.4 in) of rain over 11 days. This marks a continuation of the wetter patterns observed from the summer months, particularly following May's peak of 149 mm (5.9 in). As the transition to autumn begins, September stands out for maintaining the high rainfall typical of the preceding months, while also hinting at a gradual shift towards a drier trend in the ensuing fall months. The steady frequency of rainfall days indicates a reliable pattern, sustaining the lush surroundings before the seasonal shift, making September a key month in the hydrological calendar for this region.
In September, San Marcos experiences a moderate humidity level of 65%, which reflects a gradual rise from the summer months. The trend throughout the year shows a notable drop in humidity during July and August, reaching a low of 58%. As autumn unfolds, September marks a shift, as humidity edges upwards yet remains relatively comfortable compared to the earlier months. This creates a pleasant atmosphere, often ideal for outdoor activities, before the humidity starts to rise again in October and continues climbing towards the wetter winter months. Overall, September serves as a transitional period, balancing between the dry heat of summer and the damp coolness of fall.
In September, San Marcos experiences a notably high UV Index of 11, categorizing it in the extreme exposure bracket, with a burn time as brief as 10 minutes for unprotected skin. This marks a continuation of the intense UV levels seen throughout the summer months, peaking in June, July, and August at 12. Although the UV Index dips slightly from its summer highs, the risk remains significant, urging residents and visitors to take precautions. As fall approaches, it's crucial to stay aware of these trends to protect against sunburn and skin damage. For more detailed information, check out the San Marcos UV Index.
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As summer transitions to fall, September in San Marcos continues to bask in a generous amount of sunshine, with 277 hours of glorious sunlight gracing the skies. This month stands out as a beautiful conclusion to the summer season, retaining much of the radiance from the peak of July and August, which recorded an impressive 348 and 329 hours, respectively. While the daylight hours begin to taper off as autumn approaches, September still offers a vibrant mix of warmth and brightness, marking a significant shift from the milder sunlight seen in the earlier months of the year. Notably, the sunshine hours in September remain markedly higher than the winter months, ensuring that the spirit of summer lingers just a little longer in this charming Texan locale.
In San Marcos, September boasts a 59% chance of sunny weather, making it one of the brightest months of the year. This is a notable increase from the summer months, where July and August see lower chances of sunshine at 31% and 37%, respectively. As the season transitions from the heat of summer to the mildness of autumn, this uptick in sunny days not only heralds the onset of cooler temperatures but also invites outdoor activities and gatherings. In fact, following September, the likelihood of sun drops slightly to 52% in October, indicating that this month truly stands out as a time when residents can soak up the sun before the more overcast months set in. Overall, September serves as a beautiful bridge from summer to fall, with an enticing chance for clear skies.
As September arrives in San Marcos, daylight begins to subtly wane, transitioning from the sun-soaked splendor of summer into the gentle embrace of autumn. With an average of 12 hours of daylight, this month mirrors the longer days of both March and April, highlighting a seasonal balance before the gradual decrease that sets in with October. The trend of diminishing daylight is evident, dipping from a peak of 14 hours in June and 13 hours through July and August. As the light softens, it marks a perfect opportunity for residents to savor the beauty of the changing season, as nature transforms against the backdrop of shortening days.
As September rolls into San Marcos, the average wind speed dips to 2.5 m/s (6 mph), marking one of the calmest months of the year. This decrease follows a trend of diminishing winds during the summer, with July and August also experiencing low speeds. It's intriguing to note how the winds begin to pick up again in October, suggesting a seasonal shift that heralds the arrival of fall. Overall, September offers a serene atmosphere, ideal for outdoor activities, yet it also hints at the gentle transition toward breezier days ahead.
The weather in San Marcos 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 Marcos and find detailed weather information for every month.
September and January offer contrasting weather experiences. In September, temperatures range from a minimum of 11°C (53°F) to a scorching maximum of 38°C (100°F), with an average of 26°C (79°F). The month sees considerable rainfall totaling 112 mm (4.4 in) over about 11 days, accompanied by a humidity level of 65%. In stark contrast, January features much cooler temperatures, with a minimum of -7°C (19°F) and an average of 11°C (52°F), peaking at 26°C (80°F). Precipitation is lighter, with only 48 mm (1.9 in) over 6 days, and humidity rises to 79%. For more detailed information, you can check San Marcos weather in January.
September and February present starkly contrasting weather conditions. In September, temperatures can soar with a minimum of 11°C (53°F) and an average high of 26°C (79°F), occasionally reaching a scorching 38°C (100°F). Additionally, this month experiences a considerable amount of precipitation at 112 mm (4.4 in) spread across approximately 11 days, coupled with a humidity level of 65%. In contrast, February is much colder, featuring a minimum temperature of -15°C (6°F) and an average high reaching only 12°C (54°F), though it can get as warm as 31°C (87°F). Precipitation in February is lower, totaling 60 mm (2.4 in) over about 10 days, while the humidity rises to 79%. For a detailed look at February weather in San Marcos, you can visit San Marcos weather in February.
September and March present stark contrasts in weather conditions. In September, temperatures soar with an average high of 26°C (79°F) and can reach a scorching maximum of 38°C (100°F), while the minimum temperature is a mild 11°C (53°F). This month also sees significant rainfall, totaling 112 mm (4.4 in) over about 11 days, accompanied by a humidity level of 65%. On the other hand, March experiences much cooler temperatures, with a minimum of -3°C (27°F) and an average of 17°C (64°F), peaking at a maximum of 33°C (91°F). Rainfall in March is lighter at 67 mm (2.6 in), also spread over 11 days, and the humidity is slightly higher at 74%. For those interested in a more detailed view of the weather during this month, check out San Marcos weather in March.
When comparing the weather in September and April, we can see significant differences in temperature and humidity. September tends to be hotter, with average temperatures reaching 26°C (79°F) and maximum highs soaring up to 38°C (100°F), while April's average is cooler at 20°C (69°F) with a maximum of 35°C (94°F). In terms of precipitation, September sees more rain, averaging 112 mm (4.4 in) over 11 days, while April has slightly less at 89 mm (3.5 in) over 9 days. Additionally, April experiences higher humidity levels at 76%, compared to September’s 65%. For more detailed insights about April weather in San Marcos, you can visit San Marcos weather in April.
In comparing the weather of September and May, we can see that both months feature warm temperatures, but September usually edges out slightly warmer with averages around 26°C (79°F) and maximums reaching up to 38°C (100°F). In contrast, May has an average temperature of 25°C (76°F) and a maximum of 36°C (98°F). Additionally, May experiences higher precipitation levels, totaling 149 mm (5.9 in) over about 14 days, compared to September's 112 mm (4.4 in) over 11 days. Humidity levels in May are also higher at 81%, compared to September's 65%. For more detailed insights, you can check San Marcos weather in May.
In comparing the weather between September and June, both months experience warm temperatures, with June slightly warmer on average at 27°C (82°F) compared to September's 26°C (79°F). However, September features a wider temperature range with a maximum of 38°C (100°F), while June peaks at 37°C (100°F). Precipitation is quite similar in both months, with September receiving 112 mm (4.4 in) over 11 days and June slightly less at 102 mm (4.0 in) over 12 days. Additionally, June has higher humidity at 76% compared to September's 65%, making it feel more muggy. For more details, you can view San Marcos weather in June.
When comparing the weather in September and July, there are notable differences in temperature and precipitation. In July, temperatures range from a minimum of 17°C (63°F) to a maximum of 41°C (106°F), with an average of 29°C (84°F) and humidity at 66%. This month experiences relatively lower precipitation of 79 mm (3.1 in) over 9 days. In contrast, September sees a wider range of temperatures, with a minimum of 11°C (53°F) and a maximum of 38°C (100°F), averaging at 26°C (79°F). Moreover, September has higher precipitation levels, totaling 112 mm (4.4 in) over 11 days, while maintaining a similar humidity level of 65%. For a more detailed look at July's weather, you can visit San Marcos weather in July.
In September, the weather shows a notable shift compared to August. The minimum temperature drops to 11°C (53°F) from August's warmer 20°C (68°F), while the average temperature in September is slightly lower at 26°C (79°F) compared to 29°C (85°F) in August. Additionally, September experiences slightly less extreme maximum temperatures, peaking at 38°C (100°F) versus August’s high of 40°C (104°F). Precipitation levels remain similar, with September recording 112 mm (4.4 in) over 11 days of rain, compared to August's 111 mm (4.4 in) over just 7 days. The humidity in September is also higher at 65%, compared to August’s 58%. For more details on August weather, you can check San Marcos weather in August.
September weather tends to be significantly warmer than October, with temperatures ranging from a minimum of 11°C (53°F) to a maximum of 38°C (100°F) and an average of 26°C (79°F). In contrast, October sees a drop in temperatures, featuring a minimum of 3°C (37°F) and a maximum of 35°C (96°F), with an average temperature of 21°C (70°F). While September receives more precipitation at 112 mm (4.4 in) over 11 days, October has slightly less rainfall at 94 mm (3.7 in) across 10 days. Additionally, October has a higher humidity level at 74%, compared to September's 65%. For more details, you can check out San Marcos weather in October.
In September, the weather is marked by warm temperatures, with averages reaching up to 26°C (79°F) and maximums soaring to 38°C (100°F). The month sees considerable rainfall, totaling 112 mm (4.4 in) over about 11 days, accompanied by 65% humidity. In contrast, November brings a notable shift, with average temperatures dropping to 15°C (60°F), and nighttime lows can plummet to -3°C (26°F). Precipitation in November is significantly lighter at 49 mm (1.9 in) across just 6 days, and the humidity rises to 81%. For more detailed insights, check out San Marcos weather in November.
In September, the weather is warm, with temperatures ranging from a minimum of 11°C (53°F) to a maximum of 38°C (100°F) and an average of 26°C (79°F). The month is marked by relatively high humidity at 65%, along with significant rainfall totaling 112 mm (4.4 in) over 11 days. In contrast, December brings much cooler temperatures, with a range from -3°C (27°F) to a maximum of 29°C (84°F) and an average of 13°C (55°F). December is wetter than September, with 73 mm (2.9 in) of precipitation across just 7 days and higher humidity at 86%. For more detailed information about the weather in December, visit San Marcos weather in December.
As September rolls into San Marcos, the weather showcases a delightful transition from the scorching summer heat to more moderate temperatures. With maximums reaching 38°C (100°F), it still holds onto the warmth, but the average temperature cools down to a comfortable 26°C (79°F). This month is also characterized by increased humidity levels at 65%, which can make the warm days feel a bit more intense. With 112 mm (4.4 in) of rain spread over roughly 11 days, September introduces a refreshing shift that prepares the city for the upcoming fall months. These noteworthy changes make September a unique time to experience the vibrant climate of this beautiful region. For more insights on weather trends, check out San Marcos Climate.