San Diego Air Quality in 2020
In 2020, San Diego's air quality (San Diego-Carlsbad, CA area) had a median daily AQI of 74 (Moderate) across 366 monitored days. 49 days (13.4%) reached Unhealthy for Sensitive Groups or worse, 33 were Good, and the year's peak AQI was 192 (Unhealthy). Fine particulate matter (PM2.5) set the daily AQI on 263 of those days. The cleanest month of 2020 was March (median AQI 46, 0 days above 100) and the worst was October (median 110, 17 days above 100, peak 177).
- Good: 9.0%
- Moderate: 77.6%
- Unhealthy for Sensitive Groups: 9.6%
- Unhealthy or worse: 3.8%
Extra Protection for San Diego Homes
Air quality in San Diego 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 was San Diego's air quality in 2020?
Moderate on a typical day: median AQI 74, with 49 days above AQI 100 out of 366 monitored — the 6th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2020: 192 (Unhealthy).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 263 days.
- ✓Cleanest month: March; worst: October.
Frequently asked questions
What was the average AQI in San Diego in 2020?▾
EPA's Air Quality System puts San Diego's (San Diego-Carlsbad, CA) median daily AQI for 2020 at 74, which is Moderate. 49 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 192.
Which month had the worst air quality in San Diego in 2020?▾
The cleanest month of 2020 was March (median AQI 46, 0 days above 100) and the worst was October (median 110, 17 days above 100, peak 177).
Was 2020 a good or bad year for San Diego's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 6th cleanest by days above AQI 100. 2020's median of 74 is above the area's typical annual median of 67.
San Diego month by month in 2020
San Diego air quality month by month, 2020 (San Diego-Carlsbad, CA, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 66 | 0 | 90 | PM2.5 |
| February | 29 | 64 | 0 | 86 | PM2.5 |
| Marchcleanest | 31 | 46 | 0 | 72 | PM2.5 |
| April | 30 | 64 | 2 | 105 | O3 |
| May | 31 | 70 | 3 | 151 | PM2.5 |
| June | 30 | 64 | 2 | 154 | PM2.5 |
| July | 31 | 67 | 2 | 108 | PM2.5 |
| August | 31 | 80 | 3 | 140 | PM2.5 |
| September | 30 | 102 | 15 | 192 | PM2.5 |
| Octoberworst | 31 | 110 | 17 | 177 | PM2.5 |
| November | 30 | 85 | 4 | 104 | PM2.5 |
| December | 31 | 84 | 1 | 101 | PM2.5 |
How 2020 compares
Among the 7 years EPA has published for the area (2019–2025), 2020 ranks 6th cleanest by days above AQI 100.
2020's median of 74 is above 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 53 (PM2.5). 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.