Metro area air quality · 2025
Santa Rosa, CA
Median AQI 9 (Good). 100.0% of monitored days rated Good across this metro's EPA monitoring network.
- 9
- Median AQI
- 100.0%
- Good-air days
- 0
- Unhealthy days
- 99%
- Cleaner than US metros
Santa Rosa, CA posted a 2025 median AQI of 9 (Good) with 100.0% Good days
According to the U.S. EPA Air Quality System, the Santa Rosa, CA CBSA recorded a median AQI of 9 across 365 monitored days in 2025, with 100.0% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US metros
- The Santa Rosa, CA CBSA's 100.0% Good-day share places it cleaner than 99% of US metros in 2025.
- Closest median-AQI peer
- Evanston, WY (100.0% Good, median AQI 9) is the closest nationwide median-AQI peer to Santa Rosa, CA.
- 2020–2025 Good-day shift
- Santa Rosa, CA's Good-day share moved +20.5 points from 2020 to 2025 (median AQI -27).
- Median AQI
- Median AQI: 9
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
Santa Rosa, CA sits in the upper Good-day tercile among EPA CBSA metros on this site (100.0% of 365 monitored days). On the EPA scale the metro runs good, among the cleanest 10% of US metros, with a median AQI of 9 and 100.0% of 365 monitored days in the Good band.
- 9
- median AQI · Good
- 100.0%
- days rated Good
- 99%
- cleaner than US metros
- 39
- worst single reading
No day crossed into the Unhealthy tier across the metro's monitors in 2025.
Annual release change
What changed in the 2025 EPA annual release
- Santa Rosa, CA metro's Good-day share rose from 95.1% to 100.0% between the 2024 and 2025 EPA annual releases, a change of +4.9 percentage points.
- Santa Rosa, CA metro's median AQI fell from 19 to 9 between the 2024 and 2025 EPA annual releases, a change of -10 points.
- Santa Rosa, CA metro's peak single-day AQI fell from 72 to 39 between the 2024 and 2025 EPA annual releases, a change of -33 points.
Santa Rosa, CA sits in the upper Good-day tercile among EPA CBSA metros on this site (100.0% of 365 monitored days). Signature read: 100.0% Good-day share (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 9 over 365 measured days in 2025 (Good / Excellent). The monitored-day split lands at 365 Good (100%), 0 Moderate (0%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 17; the highest single-day reading hit 39 (Good).
Across 2020–2025, Good-day share shifted +20.5 points and median AQI moved -27 (improving). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Evanston, WY (100.0% good, AQI 9); Mayaguez, PR (97.8% good, AQI 9); Bozeman, MT (98.1% good, AQI 11).
Air Quality Summary
Median AQI
9
Good
Good Days
100.0%
365 of 365 days
Max AQI
39
Good
Health Grade
Excellent
90th pct: 17
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
365
100%
Moderate
0
0%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Santa Rosa, CA metro area's air quality is rated Excellent based on 100.0% good air days. No unhealthy air days were recorded in 2025.
Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.
How does the Santa Rosa, CA metro compare?
How Santa Rosa, CA compares
5-Year Air Quality Trend
Air quality is improving in the Santa Rosa, CA metro. Highest Good-day share: 2025 (100.0%, 365 of 365 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 290 | 69 | 6 | 36 | 199 |
| 2021 | 283 | 82 | 0 | 37 | 89 |
| 2022 | 286 | 79 | 0 | 36 | 82 |
| 2023 | 323 | 40 | 0 | 33 | 117 |
| 2024 | 348 | 18 | 0 | 19 | 72 |
| 2025 | 365 | 0 | 0 | 9 | 39 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Santa Rosa, CA (9).
Evanston, WY
Median AQI 9 · 100.0% Good-day share
Mayaguez, PR
Median AQI 9 · 97.8% Good-day share
Bozeman, MT
Median AQI 11 · 98.1% Good-day share
Show Low, AZ
Median AQI 13 · 99.5% Good-day share
Havre, MT
Median AQI 14 · 92.1% Good-day share
Ponce, PR
Median AQI 3 · 91.4% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Santa Rosa, CA's 0 (independent of median AQI).
Aberdeen, SD
0 unhealthy-or-worse days · median AQI 27
Aberdeen, WA
0 unhealthy-or-worse days · median AQI 22
Adrian, MI
0 unhealthy-or-worse days · median AQI 41
Akron, OH
0 unhealthy-or-worse days · median AQI 45
Albany, GA
0 unhealthy-or-worse days · median AQI 46
Albany, OR
0 unhealthy-or-worse days · median AQI 27
Frequently Asked Questions
How many unhealthy air days does Santa Rosa, CA have? ▼
What is the air quality in the Santa Rosa, CA metro area? ▼
Is air quality in Santa Rosa, CA getting better or worse? ▼
What does AQI 9 mean for health? ▼
How does Santa Rosa, CA compare to other metro areas? ▼
What is the 90th percentile AQI for Santa Rosa, CA? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Santa Rosa, CA, 2025. See our methodology for how AQI, median, and coverage figures are computed.
Read our methodology , how this data is sourced, computed, and verified.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary, Santa Rosa, CA · 2020–2025