Brownsville Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Brownsville (Brownsville-Harlingen, TX area) was June 26, 2020, when the daily AQI reached 184 (Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season. Across 2,557 monitored days in 2019–2025, 10 of the 10 worst days were Unhealthy (AQI 151+) or worse; 10 of the 10 were driven by fine particulate matter (PM2.5), and 8 of them fell in 2024. The cleanest day was November 10, 2023 at AQI 11 (Good); the 10 best days span 4 different years.
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When were Brownsville's worst and best air quality days?
Worst: June 26, 2020, AQI 184 (Unhealthy, PM2.5). Best: November 10, 2023, AQI 11 (Good). Based on 2,557 EPA-monitored days in the Brownsville-Harlingen, TX area, 2019–2025.
- ✓10 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 157 (Unhealthy).
- ✓Fine particulate matter (PM2.5) drove 10 of the 10 worst days.
- ✓2024 accounts for 8 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Brownsville?▾
June 26, 2020: the Brownsville-Harlingen, TX area's daily AQI hit 184 (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 Brownsville?▾
November 10, 2023, with a daily AQI of 11 (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 Brownsville's worst air quality day in 2025?▾
May 7, 2025, AQI 139 (Unhealthy for Sensitive Groups), set by fine particulate matter (PM2.5).
Which pollutant causes Brownsville's worst air days?▾
Fine particulate matter (PM2.5) set the AQI on 10 of the 10 worst days. The tables above list the defining pollutant for every day.
Brownsville's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Brownsville-Harlingen, 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) | 184 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 2 | (2024 page) | 171 | Unhealthy | PM2.5 — fine particulate matter (PM2.5) |
| 3 | (2024 page) | 170 | Unhealthy | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2024 page) | 167 | Unhealthy | PM2.5 — fine particulate matter (PM2.5) |
| 5 | (2024 page) | 164 | Unhealthy | PM2.5 — fine particulate matter (PM2.5) |
| 6 | (2024 page) | 162 | Unhealthy | PM2.5 — fine particulate matter (PM2.5) |
| 7 | (2024 page) | 158 | Unhealthy | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2024 page) | 158 | Unhealthy | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2020 page) | 158 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 10 | (2024 page) | 157 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
Worst day of each year in Brownsville
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 | 91 | Moderate | PM2.5 — fine particulate matter (PM2.5) | |
| 2020 | 184 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2021 | 99 | Moderate | PM2.5 — fine particulate matter (PM2.5) | |
| 2022 | 120 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2023 | 141 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) | |
| 2024 | 171 | Unhealthy | PM2.5 — fine particulate matter (PM2.5) | |
| 2025 | 139 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5) |
Brownsville's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Brownsville-Harlingen, TX area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2023 page) | 11 | Good | O3 — ground-level ozone |
| 2 | (2023 page) | 13 | Good | O3 — ground-level ozone |
| 3 | (2022 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2023 page) | 16 | Good | O3 — ground-level ozone |
| 5 | (2023 page) | 17 | Good | O3 — ground-level ozone |
| 6 | (2023 page) | 17 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 7 | (2022 page) | 17 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2022 page) | 18 | Good | O3 — ground-level ozone |
| 9 | (2025 page) | 19 | Good | O3 — ground-level ozone |
| 10 | (2024 page) | 19 | Good | PM2.5 — fine particulate matter (PM2.5) |
Right now in Brownsville
The latest EPA AirNow observation puts Brownsville's AQI at 47 (PM2.5). The days above are historical records, 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.