Metro area air quality · 2025
San Jose-Sunnyvale-Santa Clara, CA
Median AQI 39 (Good). 91.5% of monitored days rated Good across this metro's EPA monitoring network.
- 39
- Median AQI
- 91.5%
- Good-air days
- 0
- Unhealthy days
- 89%
- Cleaner than US metros
San Jose-Sunnyvale-Santa Clara, CA posted a 2025 median AQI of 39 (Good) with 91.5% Good days
According to the U.S. EPA Air Quality System, the San Jose-Sunnyvale-Santa Clara, CA CBSA recorded a median AQI of 39 across 365 monitored days in 2025, with 91.5% 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 San Jose-Sunnyvale-Santa Clara, CA CBSA's 91.5% Good-day share places it cleaner than 89% of US metros in 2025.
- Closest median-AQI peer
- Bay City, MI (70.4% Good, median AQI 39) is the closest nationwide median-AQI peer to San Jose-Sunnyvale-Santa Clara, CA.
- 2020–2025 Good-day shift
- San Jose-Sunnyvale-Santa Clara, CA's Good-day share moved +43.9 points from 2020 to 2025 (median AQI -13).
- Median AQI
- Median AQI: 39
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
San Jose-Sunnyvale-Santa Clara, CA sits in the upper Good-day tercile among EPA CBSA metros on this site (91.5% of 365 monitored days). On the EPA scale the metro runs good, cleaner than most US metros, with a median AQI of 39 and 91.5% of 365 monitored days in the Good band.
- 39
- median AQI · Good
- 91.5%
- days rated Good
- 89%
- cleaner than US metros
- 71
- 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
- San Jose-Sunnyvale-Santa Clara, CA metro's Good-day share rose from 50.3% to 91.5% between the 2024 and 2025 EPA annual releases, a change of +41.2 percentage points.
- San Jose-Sunnyvale-Santa Clara, CA metro's median AQI fell from 51 to 39 between the 2024 and 2025 EPA annual releases, a change of -12 points.
- San Jose-Sunnyvale-Santa Clara, CA metro's peak single-day AQI fell from 111 to 71 between the 2024 and 2025 EPA annual releases, a change of -40 points.
San Jose-Sunnyvale-Santa Clara, CA sits in the upper Good-day tercile among EPA CBSA metros on this site (91.5% of 365 monitored days). Signature read: 91.5% 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 39 over 365 measured days in 2025 (Good / Excellent). The monitored-day split lands at 334 Good (92%), 31 Moderate (8%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 50; the highest single-day reading hit 71 (Moderate).
Across 2020–2025, Good-day share shifted +43.9 points and median AQI moved -13 (improving). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Bay City, MI (70.4% good, AQI 39); Brainerd, MN (74.3% good, AQI 39); Cambridge, MD (86.0% good, AQI 39).
Air Quality Summary
Median AQI
39
Good
Good Days
91.5%
334 of 365 days
Max AQI
71
Moderate
Health Grade
Excellent
90th pct: 50
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
334
92%
Moderate
31
8%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The San Jose-Sunnyvale-Santa Clara, CA metro area's air quality is rated Excellent based on 91.5% 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 San Jose-Sunnyvale-Santa Clara, CA metro compare?
How San Jose-Sunnyvale-Santa Clara, CA compares
5-Year Air Quality Trend
Air quality is improving in the San Jose-Sunnyvale-Santa Clara, CA metro. Highest Good-day share: 2025 (91.5%, 334 of 365 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 169 | 175 | 11 | 52 | 198 |
| 2021 | 144 | 214 | 0 | 53 | 147 |
| 2022 | 183 | 177 | 0 | 50 | 119 |
| 2023 | 226 | 135 | 0 | 45 | 134 |
| 2024 | 183 | 181 | 0 | 51 | 111 |
| 2025 | 334 | 31 | 0 | 39 | 71 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near San Jose-Sunnyvale-Santa Clara, CA (39).
Bay City, MI
Median AQI 39 · 70.4% Good-day share
Brainerd, MN
Median AQI 39 · 74.3% Good-day share
Cambridge, MD
Median AQI 39 · 86.0% Good-day share
Charleston, WV
Median AQI 39 · 77.0% Good-day share
Dalton, GA
Median AQI 39 · 90.3% Good-day share
Harrisonburg, VA
Median AQI 39 · 80.0% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to San Jose-Sunnyvale-Santa Clara, 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 San Jose-Sunnyvale-Santa Clara, CA have? ▼
What is the air quality in the San Jose-Sunnyvale-Santa Clara, CA metro area? ▼
Is air quality in San Jose-Sunnyvale-Santa Clara, CA getting better or worse? ▼
What does AQI 39 mean for health? ▼
How does San Jose-Sunnyvale-Santa Clara, CA compare to other metro areas? ▼
What is the 90th percentile AQI for San Jose-Sunnyvale-Santa Clara, CA? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for San Jose-Sunnyvale-Santa Clara, 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, San Jose-Sunnyvale-Santa Clara, CA · 2020–2025