San Jose Air Quality in April
Across 2019–2025, San Jose's April air quality had a median AQI of 46 (Good) over 210 monitored days in the San Jose-Sunnyvale-Santa Clara, CA area. 0.5% of April days (1 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 61.0% of days. The cleanest April on record here was 2020 (median AQI 40, 0 days above 100) and the worst was 2022 (median 47, 1 day above 100, peak AQI 112).
- Good: 64.8%
- Moderate: 34.8%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.0%
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 April?
Good on a typical day: median AQI 46 across 2019–2025, with 0.5% of April days above AQI 100. Ground-level ozone is the main driver.
- ✓64.8% of April days were Good (AQI 0–50), 34.8% Moderate (51–100).
- ✓1 day of 210 reached AQI 101+; the April peak was 112.
- ✓Best April: 2020; worst April: 2022.
Frequently asked questions
What is the air quality like in San Jose in April?▾
Across 2019–2025, the median daily AQI in San Jose in April was 46 (Good). 64.8% of days were Good, 34.8% Moderate, and 0.5% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is April a good time for outdoor exercise in San Jose?▾
A typical April day in San Jose sits in the Good range (median AQI 46), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of April days reached AQI 101+ in 2019–2025.
Which pollutant causes San Jose's April air quality problems?▾
Ground-level ozone set the daily AQI on 61.0% of April days in San Jose. The highest April AQI recorded in 2019–2025 was 112 (Unhealthy for Sensitive Groups), in 2022.
San Jose April air quality, year by year
San Jose April 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 | 30 | 52 | 0 | 65 | PM2.5 |
| 2020cleanest | 30 | 40 | 0 | 71 | O3 |
| 2021 | 30 | 56 | 0 | 71 | PM2.5 |
| 2022worst | 30 | 47 | 1 | 112 | O3 |
| 2023 | 30 | 45 | 0 | 71 | O3 |
| 2024 | 30 | 47 | 0 | 67 | PM2.5 |
| 2025 | 30 | 44 | 0 | 49 | O3 |
What April air means in San Jose
A typical April day in San Jose sits in the Good range (median AQI 46), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of April days reached AQI 101+ in 2019–2025.
April's median AQI of 46 is below San Jose's whole-year median of 50, making it one of the area's cleaner periods. Nationally, the median April AQI across every EPA metro area (100,677 metro-days, 2019–2025) is 44, so San Jose runs in line with the national April norm; 0.5% of its April days topped AQI 100 versus 0.7% nationally (about the same).
April is part of San Jose's spring season (March, April, May); the spring 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.