San Diego Air Quality in 2025
In 2025, San Diego's air quality (San Diego-Carlsbad, CA area) had a median daily AQI of 67 (Moderate) across 365 monitored days. 33 days (9.0%) reached Unhealthy for Sensitive Groups or worse, 64 were Good, and the year's peak AQI was 161 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 180 of those days. The cleanest month of 2025 was March (median AQI 52, 0 days above 100) and the worst was August (median 84, 8 days above 100, peak 159).
- Good: 17.5%
- Moderate: 73.4%
- Unhealthy for Sensitive Groups: 7.1%
- Unhealthy or worse: 1.9%
Reduce Indoor Ozone in San Diego
Today's main pollutant in San Diego is ground-level ozone (AQI 34). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How was San Diego's air quality in 2025?
Moderate on a typical day: median AQI 67, with 33 days above AQI 100 out of 365 monitored — the 4th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2025: 161 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 180 days.
- ✓Cleanest month: March; worst: August.
Frequently asked questions
What was the average AQI in San Diego in 2025?▾
EPA's Air Quality System puts San Diego's (San Diego-Carlsbad, CA) median daily AQI for 2025 at 67, which is Moderate. 33 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 161.
Which month had the worst air quality in San Diego in 2025?▾
The cleanest month of 2025 was March (median AQI 52, 0 days above 100) and the worst was August (median 84, 8 days above 100, peak 159).
Was 2025 a good or bad year for San Diego's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2025 ranks 4th cleanest by days above AQI 100. 2025's median of 67 is in line with the area's typical annual median of 67.
San Diego month by month in 2025
San Diego air quality month by month, 2025 (San Diego-Carlsbad, CA, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 72 | 3 | 154 | PM2.5 |
| February | 28 | 69 | 0 | 100 | PM2.5 |
| Marchcleanest | 31 | 52 | 0 | 87 | PM2.5 |
| April | 30 | 60 | 1 | 126 | O3 |
| May | 31 | 74 | 5 | 151 | O3 |
| June | 30 | 76 | 7 | 161 | O3 |
| July | 31 | 74 | 4 | 136 | O3 |
| Augustworst | 31 | 84 | 8 | 159 | O3 |
| September | 30 | 55 | 0 | 87 | PM2.5 |
| October | 31 | 63 | 0 | 97 | PM2.5 |
| November | 30 | 65 | 0 | 96 | PM2.5 |
| December | 31 | 79 | 5 | 118 | PM2.5 |
How 2025 compares
Among the 7 years EPA has published for the area (2019–2025), 2025 ranks 4th cleanest by days above AQI 100.
2025's median of 67 is in line with the area's typical annual median of 67.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in San Diego
The latest EPA AirNow observation puts San Diego's AQI at 34 (O3). The figures above are multi-year annual statistics, not today's reading.
View current San Diego air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (San Diego-Carlsbad, 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.