San Antonio Air Quality in December
Across 2019–2025, San Antonio's December air quality had a median AQI of 52 (Moderate) over 217 monitored days in the San Antonio-New Braunfels, TX area. 0.9% of December days (2 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 86.6% of days. The cleanest December on record here was 2024 (median AQI 40, 0 days above 100) and the worst was 2022 (median 55, 1 day above 100, peak AQI 214).
- Good: 45.2%
- Moderate: 53.9%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.9%
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
As an Amazon Associate, we earn from qualifying purchases.
How is the air in San Antonio in December?
Moderate on a typical day: median AQI 52 across 2019–2025, with 0.9% of December days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓45.2% of December days were Good (AQI 0–50), 53.9% Moderate (51–100).
- ✓2 days of 217 reached AQI 101+; the December peak was 214.
- ✓Best December: 2024; worst December: 2022.
Frequently asked questions
What is the air quality like in San Antonio in December?▾
Across 2019–2025, the median daily AQI in San Antonio in December was 52 (Moderate). 45.2% of days were Good, 53.9% Moderate, and 0.9% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is December a good time for outdoor exercise in San Antonio?▾
A typical December day in San Antonio is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of December days 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 December air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 86.6% of December days in San Antonio. The highest December AQI recorded in 2019–2025 was 214 (Very Unhealthy), in 2022.
San Antonio December air quality, year by year
San Antonio December 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 | 31 | 54 | 0 | 85 | PM2.5 |
| 2020 | 31 | 54 | 0 | 62 | PM2.5 |
| 2021 | 31 | 58 | 0 | 87 | PM2.5 |
| 2022worst | 31 | 55 | 1 | 214 | PM2.5 |
| 2023 | 31 | 43 | 1 | 166 | PM2.5 |
| 2024cleanest | 31 | 40 | 0 | 63 | PM2.5 |
| 2025 | 31 | 47 | 0 | 86 | PM2.5 |
What December air means in San Antonio
A typical December day in San Antonio is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of December days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
December's median AQI of 52 is in line with San Antonio's whole-year median of 55, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median December AQI across every EPA metro area (95,590 metro-days, 2019–2025) is 39, so San Antonio runs above the national December norm; 0.9% of its December days topped AQI 100 versus 0.7% nationally (about the same).
December is part of San Antonio's winter season (December, January, February); the winter page pools all three months.
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 month 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.