Houston Air Quality in Fall
Across 2019–2025, Houston's fall (September–November) air quality had a median AQI of 61 (Moderate) over 637 monitored days in the Houston-The Woodlands-Sugar Land, TX area. 15.3% of fall days (98 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 54.9% of days. The cleanest fall on record here was 2019 (median AQI 54, 5 days above 100) and the worst was 2025 (median 62, 20 days above 100, peak AQI 154).
- Good: 18.2%
- Moderate: 66.4%
- Unhealthy for Sensitive Groups: 12.2%
- Unhealthy or worse: 3.1%
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How is the air in Houston in fall?
Moderate on a typical day: median AQI 61 across 2019–2025, with 15.3% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓18.2% of fall days were Good (AQI 0–50), 66.4% Moderate (51–100).
- ✓98 days of 637 reached AQI 101+; the fall peak was 192.
- ✓Cleanest month: November; worst month: September.
Frequently asked questions
What is the air quality like in Houston in fall?▾
Across 2019–2025, the median daily AQI in Houston in fall was 61 (Moderate). 18.2% of days were Good, 66.4% Moderate, and 15.3% reached Unhealthy for Sensitive Groups or worse, based on 637 monitored days in EPA's Air Quality System.
Is fall a good time for outdoor exercise in Houston?▾
A typical fall day in Houston is Moderate (median AQI 61): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 7 of fall days (15.3%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Houston's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 54.9% of fall days in Houston. The highest fall AQI recorded in 2019–2025 was 192 (Unhealthy), in 2025.
Houston fall air quality, year by year
Houston fall air quality by year (Houston-The Woodlands-Sugar Land, TX, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 91 | 54 | 5 | 169 | PM2.5 |
| 2020 | 91 | 55 | 5 | 140 | PM2.5 |
| 2021 | 91 | 68 | 15 | 166 | PM2.5 |
| 2022 | 91 | 68 | 19 | 166 | O3 |
| 2023 | 91 | 58 | 15 | 179 | PM2.5 |
| 2024 | 91 | 65 | 19 | 192 | O3 |
| 2025worst | 91 | 62 | 20 | 154 | O3 |
What fall air means in Houston
A typical fall day in Houston is Moderate (median AQI 61): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 7 of fall days (15.3%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Fall's median AQI of 61 is in line with Houston's whole-year median of 61, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Houston runs above the national Fall norm; 15.3% of its Fall days topped AQI 100 versus 1.5% nationally (above average).
Within the season, November is the cleanest month (median AQI 57, 0.0% of days above 100) and September the worst (median 74, 28.1% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Houston
The latest EPA AirNow observation puts Houston's AQI at 47 (PM2.5). The figures above are multi-year season statistics, not today's reading.
View current Houston air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Houston-The Woodlands-Sugar Land, 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.