San Jose Air Quality in 2019
In 2019, San Jose's air quality (San Jose-Sunnyvale-Santa Clara, CA area) had a median daily AQI of 48 (Good) across 365 monitored days. 4 days (1.1%) reached Unhealthy for Sensitive Groups or worse, 203 were Good, and the year's peak AQI was 136 (Unhealthy for Sensitive Groups). Fine particulate matter (PM2.5) set the daily AQI on 208 of those days. The cleanest month of 2019 was February (median AQI 39, 0 days above 100) and the worst was June (median 50, 2 days above 100, peak 136).
- Good: 55.6%
- Moderate: 43.3%
- Unhealthy for Sensitive Groups: 1.1%
- Unhealthy or worse: 0.0%
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How was San Jose's air quality in 2019?
Good on a typical day: median AQI 48, with 4 days above AQI 100 out of 365 monitored — the 4th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2019: 136 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 208 days.
- ✓Cleanest month: February; worst: June.
Frequently asked questions
What was the average AQI in San Jose in 2019?▾
EPA's Air Quality System puts San Jose's (San Jose-Sunnyvale-Santa Clara, CA) median daily AQI for 2019 at 48, which is Good. 4 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 136.
Which month had the worst air quality in San Jose in 2019?▾
The cleanest month of 2019 was February (median AQI 39, 0 days above 100) and the worst was June (median 50, 2 days above 100, peak 136).
Was 2019 a good or bad year for San Jose's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2019 ranks 4th cleanest by days above AQI 100. 2019's median of 48 is in line with the area's typical annual median of 50.
San Jose month by month in 2019
San Jose air quality month by month, 2019 (San Jose-Sunnyvale-Santa Clara, CA, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 50 | 0 | 71 | PM2.5 |
| Februarycleanest | 28 | 39 | 0 | 52 | O3 |
| March | 31 | 44 | 0 | 61 | O3 |
| April | 30 | 52 | 0 | 65 | PM2.5 |
| May | 31 | 45 | 0 | 61 | PM2.5 |
| Juneworst | 30 | 50 | 2 | 136 | PM2.5 |
| July | 31 | 52 | 1 | 126 | PM2.5 |
| August | 31 | 53 | 1 | 119 | PM2.5 |
| September | 30 | 44 | 0 | 90 | O3 |
| October | 31 | 53 | 0 | 88 | PM2.5 |
| November | 30 | 70 | 0 | 98 | PM2.5 |
| December | 31 | 48 | 0 | 62 | PM2.5 |
How 2019 compares
Among the 7 years EPA has published for the area (2019–2025), 2019 ranks 4th cleanest by days above AQI 100.
2019's median of 48 is in line with the area's typical annual median of 50.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in San Jose
The latest EPA AirNow observation puts San Jose's AQI at 44 (PM2.5). The figures above are multi-year annual statistics, not today's reading.
View current San Jose air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (San Jose-Sunnyvale-Santa Clara, 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.