San Francisco vs San Diego Air Quality Comparison
Which city has cleaner air right now, from the latest EPA AirNow AQI
As of September 24, 2026, San Francisco, CA has cleaner air than San Diego, CA — AQI 52 (Moderate) vs 57 (Moderate), a gap of 5 AQI points in the latest EPA AirNow observations. Lower AQI means cleaner air. San Francisco's reading is driven by PM2.5 and San Diego's by PM2.5.
San Francisco, CA
Moderate
San Diego, CA
Moderate
Summary
San Francisco has 5 points better air quality
San Francisco has an AQI of 52 compared to 57
Extra Protection for San Diego Homes
Air quality in San Diego is moderate (AQI 57), 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.
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5-Day Forecast Comparison
| Day | San Francisco | San Diego | Better |
|---|---|---|---|
| Today | AQI 55 | AQI 56 | San Francisco |