Santa Rosa Air Quality in October
Across 2019–2025, Santa Rosa's October air quality had a median AQI of 31 (Good) over 217 monitored days in the Santa Rosa, CA area. 1.0% of October days (2 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 42.9% of days. The cleanest October on record here was 2025 (median AQI 7, 0 days above 100) and the worst was 2020 (median 42, 2 days above 100, peak AQI 153).
- Good: 89.4%
- Moderate: 9.7%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.5%
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How is the air in Santa Rosa in October?
Good on a typical day: median AQI 31 across 2019–2025, with 1.0% of October days above AQI 100. Ground-level ozone is the main driver.
- ✓89.4% of October days were Good (AQI 0–50), 9.7% Moderate (51–100).
- ✓2 days of 217 reached AQI 101+; the October peak was 153.
- ✓Best October: 2025; worst October: 2020.
Frequently asked questions
What is the air quality like in Santa Rosa in October?▾
Across 2019–2025, the median daily AQI in Santa Rosa in October was 31 (Good). 89.4% of days were Good, 9.7% Moderate, and 1.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is October a good time for outdoor exercise in Santa Rosa?▾
A typical October day in Santa Rosa sits in the Good range (median AQI 31), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 100 of October days (1.0%) reached AQI 101+ in 2019–2025.
Which pollutant causes Santa Rosa's October air quality problems?▾
Ground-level ozone set the daily AQI on 42.9% of October days in Santa Rosa. The highest October AQI recorded in 2019–2025 was 153 (Unhealthy), in 2020.
Santa Rosa October air quality, year by year
Santa Rosa October 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 | 35 | 0 | 86 | O3 |
| 2020worst | 31 | 42 | 2 | 153 | PM2.5 |
| 2021 | 31 | 34 | 0 | 77 | O3 |
| 2022 | 31 | 32 | 0 | 55 | O3 |
| 2023 | 31 | 31 | 0 | 51 | O3 |
| 2024 | 31 | 13 | 0 | 46 | PM10 |
| 2025cleanest | 31 | 7 | 0 | 17 | PM10 |
What October air means in Santa Rosa
A typical October day in Santa Rosa sits in the Good range (median AQI 31), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 100 of October days (1.0%) reached AQI 101+ in 2019–2025.
October's median AQI of 31 is below Santa Rosa's whole-year median of 36, making it one of the area's cleaner periods. Nationally, the median October AQI across every EPA metro area (102,872 metro-days, 2019–2025) is 38, so Santa Rosa runs below the national October norm; 1.0% of its October days topped AQI 100 versus 1.3% nationally (about the same).
October is part of Santa Rosa's fall season (September, October, November); the fall 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.