San Antonio Air Quality in 2021
In 2021, San Antonio's air quality (San Antonio-New Braunfels, TX area) had a median daily AQI of 55 (Moderate) across 365 monitored days. 12 days (3.3%) reached Unhealthy for Sensitive Groups or worse, 108 were Good, and the year's peak AQI was 147 (Unhealthy for Sensitive Groups). Fine particulate matter (PM2.5) set the daily AQI on 272 of those days. The cleanest month of 2021 was November (median AQI 51, 0 days above 100) and the worst was September (median 71, 5 days above 100, peak 147).
- Good: 29.6%
- Moderate: 67.1%
- Unhealthy for Sensitive Groups: 3.3%
- Unhealthy or worse: 0.0%
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How was San Antonio's air quality in 2021?
Moderate on a typical day: median AQI 55, with 12 days above AQI 100 out of 365 monitored — the 5th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 147 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 272 days.
- ✓Cleanest month: November; worst: September.
Frequently asked questions
What was the average AQI in San Antonio in 2021?▾
EPA's Air Quality System puts San Antonio's (San Antonio-New Braunfels, TX) median daily AQI for 2021 at 55, which is Moderate. 12 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 147.
Which month had the worst air quality in San Antonio in 2021?▾
The cleanest month of 2021 was November (median AQI 51, 0 days above 100) and the worst was September (median 71, 5 days above 100, peak 147).
Was 2021 a good or bad year for San Antonio's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 5th cleanest by days above AQI 100. 2021's median of 55 is in line with the area's typical annual median of 55.
San Antonio month by month in 2021
San Antonio air quality month by month, 2021 (San Antonio-New Braunfels, TX, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 55 | 0 | 71 | PM2.5 |
| February | 28 | 53 | 0 | 70 | PM2.5 |
| March | 31 | 55 | 0 | 97 | PM2.5 |
| April | 30 | 62 | 1 | 119 | PM2.5 |
| May | 31 | 54 | 1 | 101 | PM2.5 |
| June | 30 | 55 | 1 | 108 | PM2.5 |
| July | 31 | 55 | 1 | 105 | PM2.5 |
| August | 31 | 53 | 0 | 77 | PM2.5 |
| Septemberworst | 30 | 71 | 5 | 147 | PM2.5 |
| October | 31 | 53 | 3 | 147 | PM2.5 |
| Novembercleanest | 30 | 51 | 0 | 71 | PM2.5 |
| December | 31 | 58 | 0 | 87 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 5th cleanest by days above AQI 100.
2021's median of 55 is in line with the area's typical annual median of 55.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in San Antonio
The latest EPA AirNow observation puts San Antonio's AQI at 33 (PM2.5). The figures above are multi-year annual statistics, not today's reading.
View current San Antonio air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (San Antonio-New Braunfels, TX), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.