Houston Air Quality in March

Across 2019–2025, Houston's March air quality had a median AQI of 59 (Moderate) over 217 monitored days in the Houston-The Woodlands-Sugar Land, 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 65.9% of days. The cleanest March on record here was 2020 (median AQI 56, 0 days above 100) and the worst was 2025 (median 69, 3 days above 100, peak AQI 179).

59
Median AQI
Moderate
3.7%
Days above AQI 100
8 of 217 days
85
90th percentile AQI
worst 1 day in 10
179
Peak AQI
Unhealthy
PM2.5
Main pollutant
65.9% of days
17.1%
Good days
37 of 217
  • Good: 17.1%
  • Moderate: 79.3%
  • Unhealthy for Sensitive Groups: 2.8%
  • Unhealthy or worse: 0.9%

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QUICK ANSWER

How is the air in Houston 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.

  • 17.1% of March days were Good (AQI 0–50), 79.3% Moderate (51–100).
  • 8 days of 217 reached AQI 101+; the March peak was 179.
  • Best March: 2020; worst March: 2025.

Frequently asked questions

What is the air quality like in Houston in March?

Across 2019–2025, the median daily AQI in Houston in March was 59 (Moderate). 17.1% of days were Good, 79.3% 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 Houston?

A typical March day in Houston 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 Houston's March air quality problems?

Fine particulate matter (PM2.5) set the daily AQI on 65.9% of March days in Houston. The highest March AQI recorded in 2019–2025 was 179 (Unhealthy), in 2025.

Houston March air quality, year by year

Houston March air quality by year (Houston-The Woodlands-Sugar Land, TX, EPA AQS daily AQI)

YearDays monitoredMedian AQIDays above 100Peak AQIMain pollutant
201931583129PM2.5
2020cleanest3156084PM2.5
20213157095PM2.5
202231581108PM2.5
202331661121PM2.5
202431590100PM2.5
2025worst31693179PM2.5

What March air means in Houston

A typical March day in Houston 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 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 March AQI across every EPA metro area (102,455 metro-days, 2019–2025) is 42, so Houston 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 Houston's spring season (March, April, May); the spring page pools all three months.

Activity-specific thresholds: running, cycling, kids' sports.

Right now in Houston

The latest EPA AirNow observation puts Houston's AQI at 57 (PM2.5). The figures above are multi-year month 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.