San Antonio Air Quality in Winter
Across 2019–2025, San Antonio's winter (December–February) air quality had a median AQI of 51 (Moderate) over 632 monitored days in the San Antonio-New Braunfels, TX area. 1.0% of winter days (6 of 632) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 82.0% of days. The cleanest winter on record here was 2025 (median AQI 47, 0 days above 100) and the worst was 2023 (median 45, 2 days above 100, peak AQI 309).
- Good: 48.1%
- Moderate: 50.9%
- Unhealthy for Sensitive Groups: 0.2%
- Unhealthy or worse: 0.8%
Extra Protection for San Antonio Homes
Air quality in San Antonio is moderate (AQI 52), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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How is the air in San Antonio in winter?
Moderate on a typical day: median AQI 51 across 2019–2025, with 1.0% of winter days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓48.1% of winter days were Good (AQI 0–50), 50.9% Moderate (51–100).
- ✓6 days of 632 reached AQI 101+; the winter peak was 309.
- ✓Cleanest month: February; worst month: January.
Frequently asked questions
What is the air quality like in San Antonio in winter?▾
Across 2019–2025, the median daily AQI in San Antonio in winter was 51 (Moderate). 48.1% of days were Good, 50.9% Moderate, and 1.0% reached Unhealthy for Sensitive Groups or worse, based on 632 monitored days in EPA's Air Quality System.
Is winter a good time for outdoor exercise in San Antonio?▾
A typical winter day in San Antonio is Moderate (median AQI 51): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 100 of winter days (1.0%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes San Antonio's winter air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 82.0% of winter days in San Antonio. The highest winter AQI recorded in 2019–2025 was 309 (Hazardous), in 2023.
San Antonio winter air quality, year by year
San Antonio winter air quality by year (San Antonio-New Braunfels, TX, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 90 | 53 | 1 | 175 | PM2.5 |
| 2020 | 91 | 51 | 1 | 106 | PM2.5 |
| 2021 | 90 | 55 | 0 | 87 | PM2.5 |
| 2022 | 90 | 53 | 1 | 214 | PM2.5 |
| 2023worst | 90 | 45 | 2 | 309 | PM2.5 |
| 2024 | 91 | 46 | 1 | 199 | PM2.5 |
| 2025cleanest | 90 | 47 | 0 | 86 | PM2.5 |
What winter air means in San Antonio
A typical winter day in San Antonio is Moderate (median AQI 51): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 100 of winter days (1.0%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Winter's median AQI of 51 is below San Antonio's whole-year median of 55, making it one of the area's cleaner periods. Nationally, the median Winter AQI across every EPA metro area (278,620 metro-days, 2019–2025) is 40, so San Antonio runs above the national Winter norm; 1.0% of its Winter days topped AQI 100 versus 0.6% nationally (about the same).
Within the season, February is the cleanest month (median AQI 51, 0.0% of days above 100) and January the worst (median 49, 1.9% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in San Antonio
The latest EPA AirNow observation puts San Antonio's AQI at 52 (PM2.5). The figures above are multi-year season 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.