Austin Air Quality in December
Across 2019–2025, Austin's December air quality had a median AQI of 49 (Good) over 217 monitored days in the Austin-Round Rock, TX area. 0.0% of December days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 81.6% of days. The cleanest December on record here was 2022 (median AQI 44, 0 days above 100) and the worst was 2019 (median 54, 0 days above 100, peak AQI 73).
- Good: 52.5%
- Moderate: 47.5%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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How is the air in Austin in December?
Good on a typical day: median AQI 49 across 2019–2025, with 0.0% of December days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓52.5% of December days were Good (AQI 0–50), 47.5% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the December peak was 84.
- ✓Best December: 2022; worst December: 2019.
Frequently asked questions
What is the air quality like in Austin in December?▾
Across 2019–2025, the median daily AQI in Austin in December was 49 (Good). 52.5% of days were Good, 47.5% Moderate, and 0.0% 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 Austin?▾
A typical December day in Austin sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of December days reached AQI 101+ in 2019–2025.
Which pollutant causes Austin's December air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 81.6% of December days in Austin. The highest December AQI recorded in 2019–2025 was 84 (Moderate), in 2019.
Austin December air quality, year by year
Austin December air quality by year (Austin-Round Rock, TX, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 31 | 54 | 0 | 73 | PM2.5 |
| 2020 | 31 | 49 | 0 | 72 | PM2.5 |
| 2021 | 31 | 53 | 0 | 81 | PM2.5 |
| 2022cleanest | 31 | 44 | 0 | 74 | PM2.5 |
| 2023 | 31 | 44 | 0 | 84 | PM2.5 |
| 2024 | 31 | 45 | 0 | 58 | PM2.5 |
| 2025 | 31 | 51 | 0 | 62 | PM2.5 |
What December air means in Austin
A typical December day in Austin sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of December days reached AQI 101+ in 2019–2025.
December's median AQI of 49 is in line with Austin's whole-year median of 52, 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 Austin runs above the national December norm; 0.0% of its December days topped AQI 100 versus 0.7% nationally (about the same).
December is part of Austin's winter season (December, January, February); the winter page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Austin
The latest EPA AirNow observation puts Austin's AQI at 33 (O3). The figures above are multi-year month statistics, not today's reading.
View current Austin air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Austin-Round Rock, 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.