San Diego Air Quality in August
Across 2019–2025, San Diego's August air quality had a median AQI of 77 (Moderate) over 217 monitored days in the San Diego-Carlsbad, CA area. 17.0% of August days (37 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 67.3% of days. The cleanest August on record here was 2022 (median AQI 62, 2 days above 100) and the worst was 2021 (median 77, 9 days above 100, peak AQI 126).
- Good: 3.2%
- Moderate: 79.7%
- Unhealthy for Sensitive Groups: 14.7%
- Unhealthy or worse: 2.3%
Extra Protection for San Diego Homes
Air quality in San Diego is moderate (AQI 54), 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 Diego in August?
Moderate on a typical day: median AQI 77 across 2019–2025, with 17.0% of August days above AQI 100. Ground-level ozone is the main driver.
- ✓3.2% of August days were Good (AQI 0–50), 79.7% Moderate (51–100).
- ✓37 days of 217 reached AQI 101+; the August peak was 169.
- ✓Best August: 2022; worst August: 2021.
Frequently asked questions
What is the air quality like in San Diego in August?▾
Across 2019–2025, the median daily AQI in San Diego in August was 77 (Moderate). 3.2% of days were Good, 79.7% Moderate, and 17.0% 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 Diego?▾
A typical August day in San Diego is Moderate (median AQI 77): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 6 of August days (17.0%) 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 Diego's August air quality problems?▾
Ground-level ozone set the daily AQI on 67.3% of August days in San Diego. The highest August AQI recorded in 2019–2025 was 169 (Unhealthy), in 2021.
San Diego August air quality, year by year
San Diego August air quality by year (San Diego-Carlsbad, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 80 | 5 | 169 | O3 |
| 2020 | 31 | 80 | 3 | 140 | PM2.5 |
| 2021worst | 31 | 77 | 9 | 126 | O3 |
| 2022cleanest | 31 | 62 | 2 | 115 | O3 |
| 2023 | 31 | 84 | 4 | 150 | O3 |
| 2024 | 31 | 84 | 6 | 108 | O3 |
| 2025 | 31 | 84 | 8 | 159 | O3 |
What August air means in San Diego
A typical August day in San Diego is Moderate (median AQI 77): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 6 of August days (17.0%) 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 77 is above San Diego's whole-year median of 67, making it one of the area's dirtier periods. Nationally, the median August AQI across every EPA metro area (104,152 metro-days, 2019–2025) is 45, so San Diego runs above the national August norm; 17.0% of its August days topped AQI 100 versus 3.5% nationally (above average).
August is part of San Diego's summer season (June, July, August); the summer page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in San Diego
The latest EPA AirNow observation puts San Diego's AQI at 54 (PM2.5). The figures above are multi-year month 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.