Austin Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Austin (Austin-Round Rock, TX area) was June 27, 2020, when the daily AQI reached 154 (Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season. Across 2,557 monitored days in 2019–2025, 1 of the 10 worst days was Unhealthy (AQI 151+) or worse; 6 of the 10 were driven by ground-level ozone and 3 by fine particulate matter (PM2.5), and 3 of them fell in 2024. The cleanest day was October 27, 2020 at AQI 15 (Good); the 10 best days span 5 different years.
Reduce Indoor Ozone in Austin
Today's main pollutant in Austin is ground-level ozone (AQI 33). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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When were Austin's worst and best air quality days?
Worst: June 27, 2020, AQI 154 (Unhealthy, PM2.5). Best: October 27, 2020, AQI 15 (Good). Based on 2,557 EPA-monitored days in the Austin-Round Rock, TX area, 2019–2025.
- ✓1 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 119 (Unhealthy for Sensitive Groups).
- ✓Ground-level ozone drove 6 of the 10 worst days.
- ✓2024 accounts for 3 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Austin?▾
June 27, 2020: the Austin-Round Rock, TX area's daily AQI hit 154 (Unhealthy), driven by fine particulate matter (PM2.5), in wildfire smoke season. That is the highest of 2,557 monitored days in 2019–2025.
What was the best air quality day in Austin?▾
October 27, 2020, with a daily AQI of 15 (Good). The daily AQI is the highest reading from any monitor in the area, so even the cleanest day reflects the area's worst monitor.
What was Austin's worst air quality day in 2025?▾
September 10, 2025, AQI 129 (Unhealthy for Sensitive Groups), set by ground-level ozone.
Which pollutant causes Austin's worst air days?▾
Ground-level ozone set the AQI on 6 of the 10 worst days; fine particulate matter (PM2.5) on 3. The tables above list the defining pollutant for every day.
Austin's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Austin-Round Rock, TX area (EPA AQS). The daily AQI is the highest reading from any monitor in the area that day.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2020 page) | 154 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 2 | (2024 page) | 141 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) |
| 3 | (2024 page) | 136 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
| 4 | (2025 page) | 129 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
| 5 | (2022 page) | 129 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
| 6 | (2025 page) | 126 | Unhealthy for Sensitive Groups | PM10 — coarse dust (PM10) |
| 7 | (2024 page) | 122 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 8 | (2023 page) | 122 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2025 page) | 119 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
| 10 | (2023 page) | 119 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
Worst day of each year in Austin
The single highest-AQI day in each year on record. Click a year for its full month-by-month statistics.
| Year | Worst day | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 2019 | 115 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2020 | 154 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2021 | 101 | Unhealthy for Sensitive Groups | O3 — ground-level ozone | |
| 2022 | 129 | Unhealthy for Sensitive Groups | O3 — ground-level ozone | |
| 2023 | 122 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2024 | 141 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2025 | 129 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
Austin's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Austin-Round Rock, TX area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2020 page) | 15 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 2 | (2023 page) | 19 | Good | O3 — ground-level ozone |
| 3 | (2020 page) | 19 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2019 page) | 19 | Good | O3 — ground-level ozone |
| 5 | (2025 page) | 20 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 6 | (2020 page) | 20 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 7 | (2022 page) | 21 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2022 page) | 21 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2020 page) | 21 | Good | O3 — ground-level ozone |
| 10 | (2022 page) | 22 | Good | PM2.5 — fine particulate matter (PM2.5) |
Right now in Austin
The latest EPA AirNow observation puts Austin's AQI at 33 (O3). The days above are historical records, 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.