Dallas Air Quality in September

Across 2019–2025, Dallas's September air quality had a median AQI of 68 (Moderate) over 210 monitored days in the Dallas-Fort Worth-Arlington, TX area. 28.1% of September days (59 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 73.8% of days. The cleanest September on record here was 2020 (median AQI 54, 0 days above 100) and the worst was 2023 (median 99, 14 days above 100, peak AQI 151).

68
Median AQI
Moderate
28.1%
Days above AQI 100
59 of 210 days
126
90th percentile AQI
worst 1 day in 10
179
Peak AQI
Unhealthy
O3
Main pollutant
73.8% of days
21.9%
Good days
46 of 210
  • Good: 21.9%
  • Moderate: 50.0%
  • Unhealthy for Sensitive Groups: 25.2%
  • Unhealthy or worse: 2.9%

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QUICK ANSWER

How is the air in Dallas in September?

Moderate on a typical day: median AQI 68 across 2019–2025, with 28.1% of September days above AQI 100. Ground-level ozone is the main driver.

  • 21.9% of September days were Good (AQI 0–50), 50.0% Moderate (51–100).
  • 59 days of 210 reached AQI 101+; the September peak was 179.
  • Best September: 2020; worst September: 2023.

Frequently asked questions

What is the air quality like in Dallas in September?

Across 2019–2025, the median daily AQI in Dallas in September was 68 (Moderate). 21.9% of days were Good, 50.0% Moderate, and 28.1% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.

Is September a good time for outdoor exercise in Dallas?

A typical September day in Dallas is Moderate (median AQI 68): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 4 of September days (28.1%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.

Which pollutant causes Dallas's September air quality problems?

Ground-level ozone set the daily AQI on 73.8% of September days in Dallas. The highest September AQI recorded in 2019–2025 was 179 (Unhealthy), in 2023.

Dallas September air quality, year by year

Dallas September air quality by year (Dallas-Fort Worth-Arlington, TX, EPA AQS daily AQI)

YearDays monitoredMedian AQIDays above 100Peak AQIMain pollutant
201930547156O3
2020cleanest3054097PM2.5
202130739159O3
2022309212133O3
2023worst309914151O3
202430663156O3
2025309714179O3

What September air means in Dallas

A typical September day in Dallas is Moderate (median AQI 68): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 4 of September days (28.1%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.

September's median AQI of 68 is above Dallas's whole-year median of 58, making it one of the area's dirtier periods. Nationally, the median September AQI across every EPA metro area (100,699 metro-days, 2019–2025) is 43, so Dallas runs above the national September norm; 28.1% of its September days topped AQI 100 versus 2.7% nationally (above average).

September is part of Dallas's fall season (September, October, November); the fall page pools all three months.

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

Right now in Dallas

The latest EPA AirNow observation puts Dallas's AQI at 55 (PM2.5). The figures above are multi-year month statistics, not today's reading.

View current Dallas air quality →

Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Dallas-Fort Worth-Arlington, 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.