Stockton Air Quality in January
Across 2019–2025, Stockton's January air quality had a median AQI of 62 (Moderate) over 217 monitored days in the Stockton-Lodi, CA area. 5.1% of January days (11 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 92.2% of days. The cleanest January on record here was 2023 (median AQI 40, 0 days above 100) and the worst was 2019 (median 64, 7 days above 100, peak AQI 137).
- Good: 24.4%
- Moderate: 70.5%
- Unhealthy for Sensitive Groups: 5.1%
- Unhealthy or worse: 0.0%
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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 January?
Moderate on a typical day: median AQI 62 across 2019–2025, with 5.1% of January days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓24.4% of January days were Good (AQI 0–50), 70.5% Moderate (51–100).
- ✓11 days of 217 reached AQI 101+; the January peak was 137.
- ✓Best January: 2023; worst January: 2019.
Frequently asked questions
What is the air quality like in Stockton in January?▾
Across 2019–2025, the median daily AQI in Stockton in January was 62 (Moderate). 24.4% of days were Good, 70.5% Moderate, and 5.1% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is January a good time for outdoor exercise in Stockton?▾
A typical January day in Stockton is Moderate (median AQI 62): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 20 of January days (5.1%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Stockton's January air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 92.2% of January days in Stockton. The highest January AQI recorded in 2019–2025 was 137 (Unhealthy for Sensitive Groups), in 2019.
Stockton January air quality, year by year
Stockton January air quality by year (Stockton-Lodi, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019worst | 31 | 64 | 7 | 137 | PM2.5 |
| 2020 | 31 | 60 | 0 | 97 | PM2.5 |
| 2021 | 31 | 70 | 3 | 135 | PM2.5 |
| 2022 | 31 | 80 | 1 | 106 | PM2.5 |
| 2023cleanest | 31 | 40 | 0 | 91 | PM2.5 |
| 2024 | 31 | 55 | 0 | 79 | PM2.5 |
| 2025 | 31 | 69 | 0 | 93 | PM2.5 |
What January air means in Stockton
A typical January day in Stockton is Moderate (median AQI 62): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 20 of January days (5.1%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
January's median AQI of 62 is above Stockton's whole-year median of 48, making it one of the area's dirtier periods. Nationally, the median January AQI across every EPA metro area (95,602 metro-days, 2019–2025) is 39, so Stockton runs above the national January norm; 5.1% of its January days topped AQI 100 versus 0.7% nationally (above average).
January is part of Stockton's winter season (December, January, February); the winter 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.