San Jose Air Quality in August
Across 2019–2025, San Jose's August air quality had a median AQI of 52 (Moderate) over 217 monitored days in the San Jose-Sunnyvale-Santa Clara, CA area. 6.0% of August days (13 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 53.9% of days. The cleanest August on record here was 2025 (median AQI 39, 0 days above 100) and the worst was 2020 (median 69, 9 days above 100, peak AQI 172).
- Good: 47.5%
- Moderate: 46.5%
- Unhealthy for Sensitive Groups: 4.6%
- Unhealthy or worse: 1.4%
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 August?
Moderate on a typical day: median AQI 52 across 2019–2025, with 6.0% of August days above AQI 100. Ground-level ozone is the main driver.
- ✓47.5% of August days were Good (AQI 0–50), 46.5% Moderate (51–100).
- ✓13 days of 217 reached AQI 101+; the August peak was 172.
- ✓Best August: 2025; worst August: 2020.
Frequently asked questions
What is the air quality like in San Jose in August?▾
Across 2019–2025, the median daily AQI in San Jose in August was 52 (Moderate). 47.5% of days were Good, 46.5% Moderate, and 6.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is August a good time for outdoor exercise in San Jose?▾
A typical August day in San Jose is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 17 of August days (6.0%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes San Jose's August air quality problems?▾
Ground-level ozone set the daily AQI on 53.9% of August days in San Jose. The highest August AQI recorded in 2019–2025 was 172 (Unhealthy), in 2020.
San Jose August air quality, year by year
San Jose August 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 | 31 | 53 | 1 | 119 | PM2.5 |
| 2020worst | 31 | 69 | 9 | 172 | PM2.5 |
| 2021 | 31 | 58 | 2 | 147 | PM2.5 |
| 2022 | 31 | 45 | 0 | 97 | O3 |
| 2023 | 31 | 51 | 1 | 129 | O3 |
| 2024 | 31 | 54 | 0 | 80 | O3 |
| 2025cleanest | 31 | 39 | 0 | 64 | O3 |
What August air means in San Jose
A typical August day in San Jose is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 17 of August days (6.0%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
August's median AQI of 52 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 August AQI across every EPA metro area (104,152 metro-days, 2019–2025) is 45, so San Jose runs above the national August norm; 6.0% of its August days topped AQI 100 versus 3.5% nationally (above average).
August is part of San Jose's summer season (June, July, August); the summer page pools all three months.
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 month 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.