Stockton Air Quality in Winter
Across 2019–2025, Stockton's winter (December–February) air quality had a median AQI of 60 (Moderate) over 632 monitored days in the Stockton-Lodi, CA area. 5.7% of winter days (36 of 632) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 84.8% of days. The cleanest winter on record here was 2025 (median AQI 57, 0 days above 100) and the worst was 2023 (median 59, 7 days above 100, peak AQI 114).
- Good: 31.3%
- Moderate: 63.0%
- Unhealthy for Sensitive Groups: 5.7%
- Unhealthy or worse: 0.0%
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.
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How is the air in Stockton in winter?
Moderate on a typical day: median AQI 60 across 2019–2025, with 5.7% of winter days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓31.3% of winter days were Good (AQI 0–50), 63.0% Moderate (51–100).
- ✓36 days of 632 reached AQI 101+; the winter peak was 137.
- ✓Cleanest month: February; worst month: December.
Frequently asked questions
What is the air quality like in Stockton in winter?▾
Across 2019–2025, the median daily AQI in Stockton in winter was 60 (Moderate). 31.3% of days were Good, 63.0% Moderate, and 5.7% reached Unhealthy for Sensitive Groups or worse, based on 632 monitored days in EPA's Air Quality System.
Is winter a good time for outdoor exercise in Stockton?▾
A typical winter day in Stockton is Moderate (median AQI 60): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 18 of winter days (5.7%) 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 winter air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 84.8% of winter days in Stockton. The highest winter AQI recorded in 2019–2025 was 137 (Unhealthy for Sensitive Groups), in 2023.
Stockton winter air quality, year by year
Stockton winter air quality by year (Stockton-Lodi, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 90 | 53 | 7 | 137 | PM2.5 |
| 2020 | 91 | 63 | 5 | 119 | PM2.5 |
| 2021 | 90 | 62 | 5 | 135 | PM2.5 |
| 2022 | 90 | 70 | 6 | 114 | PM2.5 |
| 2023worst | 90 | 59 | 7 | 114 | PM2.5 |
| 2024 | 91 | 55 | 6 | 129 | PM2.5 |
| 2025cleanest | 90 | 57 | 0 | 93 | PM2.5 |
What winter air means in Stockton
A typical winter day in Stockton is Moderate (median AQI 60): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 18 of winter days (5.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Winter's median AQI of 60 is above Stockton's whole-year median of 48, making it one of the area's dirtier periods. Nationally, the median Winter AQI across every EPA metro area (278,620 metro-days, 2019–2025) is 40, so Stockton runs above the national Winter norm; 5.7% of its Winter days topped AQI 100 versus 0.6% nationally (above average).
Within the season, February is the cleanest month (median AQI 52, 2.0% of days above 100) and December the worst (median 63, 9.7% above 100).
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 season 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.