Last updated: February 24, 2025
September in San Antonio brings a warm and variable climate, where temperatures can soar to a striking 39°C (102°F) while maintaining an average of 27°C (80°F). As the summer transitions to fall, the nights can cool down to a minimum of 12°C (54°F), providing a welcome respite. Rainfall is not uncommon, with an average precipitation amount of 117 mm (4.6 in) spread across about 10 days, alongside a humidity level of 65%, adding a touch of mugginess to the air. This blend of heat and occasional rain offers a unique backdrop for both residents and visitors to enjoy the vibrant city life.
In September, San Antonio experiences a pleasant transition from the sweltering heat of summer to more moderate temperatures. With minimums around 12°C (54°F) and averages hitting 27°C (80°F), the city enjoys warm days perfect for outdoor activities, while the maximum temperatures peak at 39°C (102°F), reminding residents that summer isn't quite over yet. This month's temperatures highlight a gradual decrease from the intense summer highs, making it an ideal time to explore the city's vibrant culture and scenery as the weather begins to shift. As daylight lingers, the evenings grow cooler, inviting more enjoyable outdoor experiences throughout the month.
In September, San Antonio experiences a notable spike in precipitation, receiving an impressive 117 mm (4.6 in) over approximately 10 days of rainfall. This marks a significant increase from the previous months, reflecting a transition into the wetter fall season. Following the typically dry summer months of July and August, where rainfall averages hovered between 56 mm (2.2 in) and 69 mm (2.7 in), September's downpours signal a refreshing change for the city, contributing to a total precipitation amount that is among the highest for the year. As the heat begins to wane, the increased humidity and occasional storms not only replenish the area’s water supply but also set the stage for the vibrant colors and cooler temperatures that autumn brings.
In September, San Antonio experiences a notable shift in humidity, with levels hovering around 65%. This marks a decrease from the peak summer months of July and August, where humidity plummeted to 66% and 58%, respectively. As the city transitions from the sweltering summer heat to the milder fall, humidity levels begin to rise again. This is part of a broader trend throughout the year, where San Antonio typically sees its highest humidity in the colder months, peaking at 86% in December. Overall, September offers a brief reprieve, hinting at the changing seasons while still maintaining a level of humidity that is comfortable for outdoor activities.
As summer transitions to fall in San Antonio, September maintains an UV Index of 11, categorized as extreme, requiring just 10 minutes of sun exposure before the risk of burns escalates. This trend marks a slight dip from the peak UV Index of 12 seen from June to August, yet it remains significantly high, showcasing the region's persistent sun intensity. With the UV Index generally starting at a moderate level in January and climbing through the spring and summer months, September’s readings continue to emphasize the importance of sun safety. To stay updated on the UV levels, visit San Antonio UV Index.
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As September arrives in San Antonio, the city basks in 276 hours of sunshine, marking a continuation of the sun-drenched summer months. The trend of abundant sunlight peaks during the summer, with July boasting an impressive 344 hours, while August comes in closely behind at 330 hours. Though September sees a slight dip, it still reflects the region's overall abundance of bright days that started in March with 223 hours and flourished through the warmer months. Following September, the sunshine gradually wanes as autumn takes hold, with October bringing 264 hours and the year’s remaining months trailing behind. This seasonal shift invites cooler weather while still allowing residents to enjoy a generous share of sunshine.
As September rolls around in San Antonio, the likelihood of sunny weather rises to an impressive 61%, marking it as one of the sunniest months of the year. Compared to the drier summer months, where chances dip to 34% in both July and August, September brings a refreshing shift in weather patterns. This trend highlights a welcome transition; while spring months like April and May display lower percentages of sunshine, the approach of fall showcases a significant uptick, making the early autumn days perfect for outdoor activities. Overall, September stands out, offering a delightful blend of warm temperatures and abundant sunshine, ideal for enjoying the city's vibrant landscapes.
In September, San Antonio experiences a slight decline in daylight, offering about 12 hours of sunshine each day. This marks a transition from the prolonged daylight of the summer months, where residents enjoyed up to 13 hours of sunlight from May through August. As autumn approaches, the days gradually shorten, with sunlight tapering off further in October. Interestingly, the pattern reflects a natural ebb and flow: after an increase in daylight during the spring, a peak in summer, and now a seasonal retreat, San Antonio's daylight duration serves as a reminder of the rhythmic changes in nature throughout the year.
As summer gives way to autumn, September in San Antonio experiences a gentle decline in wind speed, averaging 2.5 m/s (6 mph). This marks a notable shift from the breezier spring months, where speeds peaked at 4.0 m/s (9 mph) in March. The trend of decreasing winds continues from previous months, with August and July also recording their lowest averages of 2.6 m/s (6 mph). This consistent lack of strong winds during late summer and early fall brings a serene calmness to the city, making it an ideal time for leisurely outdoor activities as residents savor the transition into the cooler autumn days ahead.
The weather in San Antonio 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 Antonio and find detailed weather information for every month.
When comparing the weather in September and January, significant differences emerge in temperature and precipitation. September boasts a warmer climate with average temperatures reaching 27°C (80°F) and highs soaring up to 39°C (102°F), accompanied by about 117 mm (4.6 in) of rain over 10 days. In contrast, January experiences much cooler conditions, with temperatures ranging from a minimum of -7°C (20°F) to an average of 11°C (53°F), and a maximum of 27°C (81°F). Moreover, January sees significantly less precipitation, recording only 44 mm (1.7 in) over 6 days. The humidity in January is higher at 79%, compared to 65% in September, adding to the distinct seasonal atmospheres of these months. For a more detailed insight, refer to San Antonio weather in January.
When comparing the weather in September and February, it's clear that these months present stark contrasts. September boasts a much warmer climate, with average temperatures around 27°C (80°F) and highs reaching up to 39°C (102°F), accompanied by significant humidity at 65% and notable precipitation of 117 mm (4.6 in) over about 10 days. In contrast, February brings a chillier atmosphere, where temperatures average 13°C (55°F) and can drop to a brisk -12°C (10°F) at night. This month also sees lower precipitation at 58 mm (2.3 in) and higher humidity levels at 79%. For more specific details, you can check out San Antonio weather in February.
In September, the weather is notably warmer with average temperatures around 27°C (80°F), peaking at a scorching 39°C (102°F), while the minimum temperature rarely drops below 12°C (54°F). The month is also marked by higher precipitation levels, totaling 117 mm (4.6 in) over about 10 days, with humidity sitting at 65%. In contrast, March presents much cooler conditions, with average temperatures around 18°C (65°F) and a maximum of 33°C (91°F), while the minimum can plummet to -3°C (27°F). The precipitation is lower at 62 mm (2.5 in) over 9 days, and humidity is slightly higher at 74%. For more details on the weather in March, you can check San Antonio weather in March.
When comparing the weather in September and April, distinct differences emerge. September tends to be much warmer, with average temperatures around 27°C (80°F) and highs reaching up to 39°C (102°F), while April has a milder average of 21°C (70°F), peaking at 35°C (95°F). September also experiences higher precipitation, with 117 mm (4.6 in) over 10 days compared to April's 71 mm (2.8 in) across 8 days. Additionally, humidity is slightly lower in September at 65%, while April experiences higher humidity levels at 76%. For more details on April weather, check out San Antonio weather in April.
Comparing the weather in September and May reveals notable differences. September experiences higher average temperatures, with daily highs reaching up to 39°C (102°F) and an average of 27°C (80°F), while May settles at a cooler average of 25°C (77°F) and maxing out at 37°C (99°F). Both months have considerable precipitation, but May is slightly wetter with 130 mm (5.1 in) over 15 days, compared to September's 117 mm (4.6 in) over 10 days. Additionally, humidity levels are higher in May at 81%, compared to September's 65%. For more information, you can check San Antonio weather in May.
In comparing the weather of September and June, both months experience similar maximum temperatures, peaking at around 39°C (102°F to 103°F). However, September boasts a wider range of temperatures, with minimums dropping down to 12°C (54°F), while June maintains a warmer minimum of 18°C (64°F). Precipitation levels also differ; September receives more rainfall, totaling 117 mm (4.6 in) over 10 days, compared to June's 78 mm (3.1 in) over 12 days. Additionally, humidity is slightly lower in September at 65% versus June's higher average of 76%. For a more detailed look at June weather, you can check out San Antonio weather in June.
When comparing the weather in July and September, we see both similarities and differences. July tends to be slightly warmer, with average temperatures around 29°C (85°F) and a maximum of 41°C (106°F), compared to September's average of 27°C (80°F) with a high of 39°C (102°F). However, September experiences more precipitation, with 117 mm (4.6 in) over about 10 days, whereas July receives only 69 mm (2.7 in) over 8 days. Humidity levels are quite similar in both months, with July at 66% and September at 65%. For more detailed information, check out San Antonio weather in July.
In comparing the weather of September and August, September tends to be slightly cooler, with average temperatures ranging from a minimum of 12°C (54°F) to a maximum of 39°C (102°F), whereas August sees warmer averages, starting at 20°C (69°F) and peaking at 40°C (103°F). Additionally, September experiences more precipitation, totaling 117 mm (4.6 in) over 10 days, while August is drier, with only 56 mm (2.2 in) of rain across 6 days. Humidity levels are also higher in September at 65% compared to August's 58%. For more detailed information, you can check San Antonio weather in August.
September and October exhibit notable differences in weather patterns. September tends to be hotter, with average temperatures around 27°C (80°F) and a maximum reaching up to 39°C (102°F), while in October, the average cools to 22°C (72°F) with highs of 37°C (98°F). Precipitation is slightly lower in October at 89 mm (3.5 in) compared to September's 117 mm (4.6 in), though both months experience rain on about 10 days. Additionally, humidity rises a bit from 65% in September to 74% in October, contributing to a more comfortable, albeit slightly wetter, October. For more detailed insights, you can check San Antonio weather in October.
In September, temperatures are significantly warmer, with a minimum of 12°C (54°F) and an average of 27°C (80°F), reaching a maximum of 39°C (102°F). This month also experiences considerable rainfall, totaling 117 mm (4.6 in) over approximately 10 days, and humidity levels are around 65%. In contrast, November sees much cooler temperatures, with a minimum of -4°C (25°F) and an average of 16°C (61°F), peaking at a maximum of 32°C (90°F). Precipitation decreases to 46 mm (1.8 in) spread over just 6 days, accompanied by higher humidity levels of 81%. For more details on November weather, check out San Antonio weather in November.
In September, the weather is hot, with temperatures ranging from a minimum of 12°C (54°F) to a scorching maximum of 39°C (102°F) and an average of 27°C (80°F). This month experiences a fair amount of rainfall, with 117 mm (4.6 in) of precipitation spread over about 10 days, coupled with a humidity level of 65%. In contrast, December brings much cooler temperatures, with a minimum of -3°C (27°F), an average of 13°C (56°F), and a maximum of 29°C (85°F). Precipitation decreases to 57 mm (2.3 in) over about 7 days, while humidity rises to 86%, creating a crisp yet damp atmosphere. For more insights, check out San Antonio weather in December.
As September arrives in San Antonio, the weather showcases a notable transition from the intense summer heat, with temperatures averaging a comfortable 27°C (80°F) after sweltering highs that can reach up to 39°C (102°F). This month also brings a modest increase in precipitation, leading to a refreshing change, as rain graces the area about 10 days out of the month. While humidity remains at a balmy 65%, the overall climate feels more moderate compared to the preceding summer months. For a comprehensive overview of the annual weather patterns, be sure to check out San Antonio Climate.