Santa Rosa Air Quality in January
Across 2019–2025, Santa Rosa's January air quality had a median AQI of 35 (Good) over 217 monitored days in the Santa Rosa, CA area. 0.0% of January days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 58.1% of days. The cleanest January on record here was 2025 (median AQI 14, 0 days above 100) and the worst was 2022 (median 54, 0 days above 100, peak AQI 65).
- Good: 78.3%
- Moderate: 21.7%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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How is the air in Santa Rosa in January?
Good on a typical day: median AQI 35 across 2019–2025, with 0.0% of January days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓78.3% of January days were Good (AQI 0–50), 21.7% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the January peak was 83.
- ✓Best January: 2025; worst January: 2022.
Frequently asked questions
What is the air quality like in Santa Rosa in January?▾
Across 2019–2025, the median daily AQI in Santa Rosa in January was 35 (Good). 78.3% of days were Good, 21.7% Moderate, and 0.0% 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 Santa Rosa?▾
A typical January day in Santa Rosa sits in the Good range (median AQI 35), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of January days reached AQI 101+ in 2019–2025.
Which pollutant causes Santa Rosa's January air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 58.1% of January days in Santa Rosa. The highest January AQI recorded in 2019–2025 was 83 (Moderate), in 2022.
Santa Rosa January air quality, year by year
Santa Rosa January air quality by year (Santa Rosa, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 39 | 0 | 83 | PM2.5 |
| 2020 | 31 | 35 | 0 | 64 | PM2.5 |
| 2021 | 31 | 46 | 0 | 71 | PM2.5 |
| 2022worst | 31 | 54 | 0 | 65 | PM2.5 |
| 2023 | 31 | 37 | 0 | 55 | PM2.5 |
| 2024 | 31 | 31 | 0 | 48 | O3 |
| 2025cleanest | 31 | 14 | 0 | 39 | PM10 |
What January air means in Santa Rosa
A typical January day in Santa Rosa sits in the Good range (median AQI 35), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of January days reached AQI 101+ in 2019–2025.
January's median AQI of 35 is in line with Santa Rosa's whole-year median of 36, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median January AQI across every EPA metro area (95,602 metro-days, 2019–2025) is 39, so Santa Rosa runs below the national January norm; 0.0% of its January days topped AQI 100 versus 0.7% nationally (about the same).
January is part of Santa Rosa's winter season (December, January, February); the winter page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Santa Rosa
The latest EPA AirNow observation puts Santa Rosa's AQI at 36 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Santa Rosa air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Santa Rosa, 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.