Stockton Air Quality in September
Across 2019–2025, Stockton's September air quality had a median AQI of 52 (Moderate) over 210 monitored days in the Stockton-Lodi, CA area. 6.7% of September days (14 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 47.1% of days. The cleanest September on record here was 2025 (median AQI 48, 0 days above 100) and the worst was 2020 (median 85, 10 days above 100, peak AQI 215).
- Good: 45.2%
- Moderate: 48.1%
- Unhealthy for Sensitive Groups: 2.9%
- Unhealthy or worse: 3.8%
Extra Protection for Stockton Homes
Air quality in Stockton is moderate (AQI 60), with particle pollution the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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How is the air in Stockton in September?
Moderate on a typical day: median AQI 52 across 2019–2025, with 6.7% of September days above AQI 100. Ground-level ozone is the main driver.
- ✓45.2% of September days were Good (AQI 0–50), 48.1% Moderate (51–100).
- ✓14 days of 210 reached AQI 101+; the September peak was 215.
- ✓Best September: 2025; worst September: 2020.
Frequently asked questions
What is the air quality like in Stockton in September?▾
Across 2019–2025, the median daily AQI in Stockton in September was 52 (Moderate). 45.2% of days were Good, 48.1% Moderate, and 6.7% 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 Stockton?▾
A typical September day in Stockton is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 15 of September days (6.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Stockton's September air quality problems?▾
Ground-level ozone set the daily AQI on 47.1% of September days in Stockton. The highest September AQI recorded in 2019–2025 was 215 (Very Unhealthy), in 2020.
Stockton September air quality, year by year
Stockton September air quality by year (Stockton-Lodi, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 30 | 39 | 1 | 122 | O3 |
| 2020worst | 30 | 85 | 10 | 215 | PM2.5 |
| 2021 | 30 | 60 | 0 | 82 | PM2.5 |
| 2022 | 30 | 53 | 1 | 208 | O3 |
| 2023 | 30 | 45 | 1 | 107 | PM2.5 |
| 2024 | 30 | 51 | 1 | 112 | O3 |
| 2025cleanest | 30 | 48 | 0 | 74 | O3 |
What September air means in Stockton
A typical September day in Stockton is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 15 of September days (6.7%) 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 52 is above Stockton's whole-year median of 48, 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 Stockton runs above the national September norm; 6.7% of its September days topped AQI 100 versus 2.7% nationally (above average).
September is part of Stockton's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Stockton
The latest EPA AirNow observation puts Stockton's AQI at 60 (PM10). The figures above are multi-year month statistics, not today's reading.
View current Stockton air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Stockton-Lodi, CA), 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.