Stockton Air Quality in December
Across 2019–2025, Stockton's December air quality had a median AQI of 63 (Moderate) over 217 monitored days in the Stockton-Lodi, CA area. 9.7% of December days (21 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 91.2% of days. The cleanest December on record here was 2019 (median AQI 53, 0 days above 100) and the worst was 2024 (median 70, 6 days above 100, peak AQI 129).
- Good: 23.0%
- Moderate: 67.3%
- Unhealthy for Sensitive Groups: 9.7%
- 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 December?
Moderate on a typical day: median AQI 63 across 2019–2025, with 9.7% of December days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓23.0% of December days were Good (AQI 0–50), 67.3% Moderate (51–100).
- ✓21 days of 217 reached AQI 101+; the December peak was 129.
- ✓Best December: 2019; worst December: 2024.
Frequently asked questions
What is the air quality like in Stockton in December?▾
Across 2019–2025, the median daily AQI in Stockton in December was 63 (Moderate). 23.0% of days were Good, 67.3% Moderate, and 9.7% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is December a good time for outdoor exercise in Stockton?▾
A typical December day in Stockton is Moderate (median AQI 63): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 10 of December days (9.7%) 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 December air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 91.2% of December days in Stockton. The highest December AQI recorded in 2019–2025 was 129 (Unhealthy for Sensitive Groups), in 2024.
Stockton December air quality, year by year
Stockton December air quality by year (Stockton-Lodi, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 31 | 53 | 0 | 86 | PM2.5 |
| 2020 | 31 | 72 | 5 | 119 | PM2.5 |
| 2021 | 31 | 55 | 2 | 117 | PM2.5 |
| 2022 | 31 | 64 | 3 | 114 | PM2.5 |
| 2023 | 31 | 69 | 5 | 111 | PM2.5 |
| 2024worst | 31 | 70 | 6 | 129 | PM2.5 |
| 2025 | 31 | 59 | 0 | 87 | PM2.5 |
What December air means in Stockton
A typical December day in Stockton is Moderate (median AQI 63): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 10 of December days (9.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
December's median AQI of 63 is above Stockton's whole-year median of 48, making it one of the area's dirtier periods. Nationally, the median December AQI across every EPA metro area (95,590 metro-days, 2019–2025) is 39, so Stockton runs above the national December norm; 9.7% of its December days topped AQI 100 versus 0.7% nationally (above average).
December 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.