Brownsville Air Quality in March
Across 2019–2025, Brownsville's March air quality had a median AQI of 59 (Moderate) over 217 monitored days in the Brownsville-Harlingen, TX area. 3.7% of March days (8 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 86.6% of days. The cleanest March on record here was 2019 (median AQI 53, 0 days above 100) and the worst was 2024 (median 74, 6 days above 100, peak AQI 139).
- Good: 19.8%
- Moderate: 76.5%
- Unhealthy for Sensitive Groups: 3.7%
- Unhealthy or worse: 0.0%
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How is the air in Brownsville in March?
Moderate on a typical day: median AQI 59 across 2019–2025, with 3.7% of March days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓19.8% of March days were Good (AQI 0–50), 76.5% Moderate (51–100).
- ✓8 days of 217 reached AQI 101+; the March peak was 139.
- ✓Best March: 2019; worst March: 2024.
Frequently asked questions
What is the air quality like in Brownsville in March?▾
Across 2019–2025, the median daily AQI in Brownsville in March was 59 (Moderate). 19.8% of days were Good, 76.5% Moderate, and 3.7% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is March a good time for outdoor exercise in Brownsville?▾
A typical March day in Brownsville is Moderate (median AQI 59): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 27 of March days (3.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Brownsville's March air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 86.6% of March days in Brownsville. The highest March AQI recorded in 2019–2025 was 139 (Unhealthy for Sensitive Groups), in 2024.
Brownsville March air quality, year by year
Brownsville March air quality by year (Brownsville-Harlingen, TX, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 31 | 53 | 0 | 77 | PM2.5 |
| 2020 | 31 | 60 | 0 | 76 | PM2.5 |
| 2021 | 31 | 57 | 0 | 82 | PM2.5 |
| 2022 | 31 | 54 | 0 | 85 | PM2.5 |
| 2023 | 31 | 61 | 0 | 90 | PM2.5 |
| 2024worst | 31 | 74 | 6 | 139 | PM2.5 |
| 2025 | 31 | 58 | 2 | 138 | PM2.5 |
What March air means in Brownsville
A typical March day in Brownsville is Moderate (median AQI 59): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 27 of March days (3.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
March's median AQI of 59 is above Brownsville's whole-year median of 52, making it one of the area's dirtier periods. Nationally, the median March AQI across every EPA metro area (102,455 metro-days, 2019–2025) is 42, so Brownsville runs above the national March norm; 3.7% of its March days topped AQI 100 versus 0.4% nationally (above average).
March is part of Brownsville's spring season (March, April, May); the spring page pools all three months.
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 month 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.