San Francisco vs San Diego Air Quality Comparison
Which city has cleaner air right now, from the latest EPA AirNow AQI
As of September 16, 2026, San Francisco, CA has cleaner air than San Diego, CA — AQI 36 (Good) vs 54 (Moderate), a gap of 18 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
Good
San Diego, CA
Moderate
Summary
San Francisco has 18 points better air quality
San Francisco has an AQI of 36 compared to 54
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.
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5-Day Forecast Comparison
| Day | San Francisco | San Diego | Better |
|---|---|---|---|
| Today | AQI 44 | AQI 55 | San Francisco |
| Wed, Sep 16 | AQI 50 | AQI 55 | San Francisco |