Oakland Air Quality in Winter
Across 2019–2025, Oakland's winter (December–February) air quality had a median AQI of 52 (Moderate) over 562 monitored days in the San Francisco-Oakland-Hayward, CA area. 0.4% of winter days (2 of 562) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 84.9% of days. The cleanest winter on record here was 2025 (median AQI 19, 0 days above 100) and the worst was 2022 (median 58, 1 day above 100, peak AQI 105).
- Good: 42.3%
- Moderate: 57.3%
- Unhealthy for Sensitive Groups: 0.4%
- Unhealthy or worse: 0.0%
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How is the air in Oakland in winter?
Moderate on a typical day: median AQI 52 across 2019–2025, with 0.4% of winter days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓42.3% of winter days were Good (AQI 0–50), 57.3% Moderate (51–100).
- ✓2 days of 562 reached AQI 101+; the winter peak was 105.
- ✓Cleanest month: February; worst month: December.
Frequently asked questions
What is the air quality like in Oakland in winter?▾
Across 2019–2025, the median daily AQI in Oakland in winter was 52 (Moderate). 42.3% of days were Good, 57.3% Moderate, and 0.4% reached Unhealthy for Sensitive Groups or worse, based on 562 monitored days in EPA's Air Quality System.
Is winter a good time for outdoor exercise in Oakland?▾
A typical winter day in Oakland is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of winter days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Oakland's winter air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 84.9% of winter days in Oakland. The highest winter AQI recorded in 2019–2025 was 105 (Unhealthy for Sensitive Groups), in 2022.
Oakland winter air quality, year by year
Oakland winter air quality by year (San Francisco-Oakland-Hayward, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 90 | 46 | 0 | 89 | PM2.5 |
| 2020 | 91 | 53 | 0 | 100 | PM2.5 |
| 2021 | 90 | 52 | 0 | 92 | PM2.5 |
| 2022worst | 90 | 58 | 1 | 105 | PM2.5 |
| 2023 | 90 | 53 | 0 | 83 | PM2.5 |
| 2024 | 91 | 53 | 1 | 105 | PM2.5 |
| 2025cleanest | 20 | 19 | 0 | 32 | PM2.5 |
What winter air means in Oakland
A typical winter day in Oakland is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of winter days 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 52 is in line with Oakland's whole-year median of 53, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Winter AQI across every EPA metro area (278,620 metro-days, 2019–2025) is 40, so Oakland runs above the national Winter norm; 0.4% of its Winter days topped AQI 100 versus 0.6% nationally (about the same).
Within the season, February is the cleanest month (median AQI 46, 0.0% of days above 100) and December the worst (median 55, 1.1% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Oakland
The latest EPA AirNow observation puts Oakland's AQI at 37 (PM2.5). The figures above are multi-year season statistics, not today's reading.
View current Oakland air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (San Francisco-Oakland-Hayward, 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.