San Jose Air Quality in Summer
Across 2019–2025, San Jose's summer (June–August) air quality had a median AQI of 49 (Good) over 644 monitored days in the San Jose-Sunnyvale-Santa Clara, CA area. 3.3% of summer days (21 of 644) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 54.3% of days. The cleanest summer on record here was 2025 (median AQI 41, 0 days above 100) and the worst was 2020 (median 49, 9 days above 100, peak AQI 172).
- Good: 52.5%
- Moderate: 44.3%
- Unhealthy for Sensitive Groups: 2.8%
- Unhealthy or worse: 0.5%
Extra Protection for San Jose Homes
Air quality in San Jose is moderate (AQI 53), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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How is the air in San Jose in summer?
Good on a typical day: median AQI 49 across 2019–2025, with 3.3% of summer days above AQI 100. Ground-level ozone is the main driver.
- ✓52.5% of summer days were Good (AQI 0–50), 44.3% Moderate (51–100).
- ✓21 days of 644 reached AQI 101+; the summer peak was 172.
- ✓Cleanest month: June; worst month: August.
Frequently asked questions
What is the air quality like in San Jose in summer?▾
Across 2019–2025, the median daily AQI in San Jose in summer was 49 (Good). 52.5% of days were Good, 44.3% Moderate, and 3.3% reached Unhealthy for Sensitive Groups or worse, based on 644 monitored days in EPA's Air Quality System.
Is summer a good time for outdoor exercise in San Jose?▾
A typical summer day in San Jose sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 30 of summer days (3.3%) reached AQI 101+ in 2019–2025.
Which pollutant causes San Jose's summer air quality problems?▾
Ground-level ozone set the daily AQI on 54.3% of summer days in San Jose. The highest summer AQI recorded in 2019–2025 was 172 (Unhealthy), in 2020.
San Jose summer air quality, year by year
San Jose summer air quality by year (San Jose-Sunnyvale-Santa Clara, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 92 | 52 | 4 | 136 | PM2.5 |
| 2020worst | 92 | 49 | 9 | 172 | PM2.5 |
| 2021 | 92 | 53 | 3 | 147 | PM2.5 |
| 2022 | 92 | 46 | 0 | 97 | O3 |
| 2023 | 92 | 50 | 3 | 129 | O3 |
| 2024 | 92 | 55 | 2 | 111 | PM2.5 |
| 2025cleanest | 92 | 41 | 0 | 67 | O3 |
What summer air means in San Jose
A typical summer day in San Jose sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 30 of summer days (3.3%) reached AQI 101+ in 2019–2025.
Summer's median AQI of 49 is in line with San Jose's whole-year median of 50, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Summer AQI across every EPA metro area (308,645 metro-days, 2019–2025) is 46, so San Jose runs in line with the national Summer norm; 3.3% of its Summer days topped AQI 100 versus 3.6% nationally (about the same).
Within the season, June is the cleanest month (median AQI 47, 1.4% of days above 100) and August the worst (median 52, 6.0% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in San Jose
The latest EPA AirNow observation puts San Jose's AQI at 53 (PM2.5). The figures above are multi-year season 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.