Brownsville Air Quality in Fall
Across 2019–2025, Brownsville's fall (September–November) air quality had a median AQI of 44 (Good) over 637 monitored days in the Brownsville-Harlingen, TX area. 1.0% of fall days (6 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 67.2% of days. The cleanest fall on record here was 2023 (median AQI 38, 0 days above 100) and the worst was 2024 (median 55, 3 days above 100, peak AQI 152).
- Good: 60.3%
- Moderate: 38.8%
- Unhealthy for Sensitive Groups: 0.8%
- Unhealthy or worse: 0.2%
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How is the air in Brownsville in fall?
Good on a typical day: median AQI 44 across 2019–2025, with 1.0% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓60.3% of fall days were Good (AQI 0–50), 38.8% Moderate (51–100).
- ✓6 days of 637 reached AQI 101+; the fall peak was 152.
- ✓Cleanest month: November; worst month: September.
Frequently asked questions
What is the air quality like in Brownsville in fall?▾
Across 2019–2025, the median daily AQI in Brownsville in fall was 44 (Good). 60.3% of days were Good, 38.8% Moderate, and 1.0% 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 Brownsville?▾
A typical fall day in Brownsville sits in the Good range (median AQI 44), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 100 of fall days (1.0%) reached AQI 101+ in 2019–2025.
Which pollutant causes Brownsville's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 67.2% of fall days in Brownsville. The highest fall AQI recorded in 2019–2025 was 152 (Unhealthy), in 2024.
Brownsville fall air quality, year by year
Brownsville fall air quality by year (Brownsville-Harlingen, TX, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 91 | 41 | 0 | 79 | PM2.5 |
| 2020 | 91 | 46 | 1 | 101 | PM2.5 |
| 2021 | 91 | 43 | 0 | 89 | PM2.5 |
| 2022 | 91 | 40 | 0 | 68 | PM2.5 |
| 2023cleanest | 91 | 38 | 0 | 67 | O3 |
| 2024worst | 91 | 55 | 3 | 152 | PM2.5 |
| 2025 | 91 | 58 | 2 | 123 | PM2.5 |
What fall air means in Brownsville
A typical fall day in Brownsville sits in the Good range (median AQI 44), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 100 of fall days (1.0%) reached AQI 101+ in 2019–2025.
Fall's median AQI of 44 is below Brownsville's whole-year median of 52, making it one of the area's cleaner periods. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Brownsville runs above the national Fall norm; 1.0% of its Fall days topped AQI 100 versus 1.5% nationally (about the same).
Within the season, November is the cleanest month (median AQI 41, 0.5% of days above 100) and September the worst (median 45, 1.5% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Brownsville
The latest EPA AirNow observation puts Brownsville's AQI at 47 (PM2.5). The figures above are multi-year season statistics, not today's reading.
View current Brownsville air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Brownsville-Harlingen, 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.