San Francisco Median AQI 2025: Historical Air Quality Data
Explore 2025 air quality data for San Francisco, including the median AQI, seasonal patterns, pollution trends, and how air quality changed over the year.
Current Air Quality
Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Extra Protection for San Francisco Homes
Air quality in San Francisco is moderate (AQI 59), 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: Levoit Core 400S — True HEPA · CADR ~260 CFM · rooms up to 403 sq ft
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San Francisco Air Quality in 2025
Historical air quality data for San Francisco in 2025 shows how pollution levels have changed over time. Understanding yearly trends helps identify seasonal patterns, the impact of local policies, and long-term air quality improvements or concerns in your area. Check current conditions below for today's AQI reading.
View Current San Francisco Air Quality →San Francisco 2025 Air Quality Snapshot
Across 2025, San Francisco's median AQI was around 63 (Moderate), based on current readings and seasonal patterns for the San Francisco-Oakland-Fremont reporting area. That means a typical day fell near AQI 63, with the dominant pollutant being fine particulate matter (PM2.5), which is common for the West Coast region.
How San Francisco Air Quality Changed by Season in 2025
Spring (Mar–May): Usually San Francisco's cleanest stretch, with AQI near 45. Mild temperatures and better atmospheric mixing keep both ozone and particulates low.
Summer (Jun–Aug): AQI climbs toward 71 as heat and sunlight drive higher ozone and, in the West, wildfire-smoke episodes. Afternoons are the worst time to be outside.
Fall (Sep–Nov): Air quality generally improves as temperatures drop, though early fall can still carry wildfire smoke in the West Coast region.
Winter (Dec–Feb): AQI near 83. Cold-air temperature inversions can trap PM2.5 from heating and vehicles close to the ground, especially on still mornings.
Is It Safe to Exercise Outside in San Francisco?
With San Francisco's AQI at 59 (Moderate), outdoor exercise is generally safe for most people. If you have asthma, heart or lung conditions, or are exercising children or older adults, schedule strenuous workouts for the early morning (6–10 AM) when PM2.5 levels are lowest and watch for symptoms like coughing or chest tightness.
See our running & AQI guide and cycling & AQI guide for activity-specific thresholds.
What's Causing San Francisco's Air Pollution?
In San Francisco, the leading pollutant is fine particulate matter (PM2.5). As part of the West Coast region, the main drivers of air pollution here are:
- •Vehicle emissions from heavily trafficked freeways and urban corridors
- •Seasonal wildfire smoke drifting in from forest fires across the West
- •Port, shipping, and warehouse logistics activity
- •Agricultural operations and dust in nearby valleys
Dig deeper: San Francisco PM2.5 levels · San Francisco ozone levels
Air Purifier & Monitor Buying Guides
Not sure which device fits your needs? Our hands-on guides break down the best picks by use case.
PM2.5 Levels
Fine particulate matter data →
Ozone Levels
Ground-level ozone data →
Seasonal Guides
Air quality by season →
Health Effects
Learn about air pollution impacts →
Frequently Asked Questions About San Francisco Air Quality
What is the current air quality in San Francisco?
The current Air Quality Index (AQI) in San Francisco, CA is 59, which is considered moderate.
Is it safe to exercise outdoors in San Francisco?
Generally yes. With an AQI of 59, outdoor exercise is acceptable for most people. Sensitive individuals should monitor symptoms.
When is the best time of year to visit San Francisco for good air quality?
Spring and early fall typically offer the best air quality in San Francisco. Summer months may have elevated ozone levels, while winter can see higher PM2.5 from temperature inversions.
What causes air pollution in San Francisco?
Air pollution in San Francisco can come from vehicle emissions, industrial activity, construction, wildfires, and weather patterns. Local geography and seasonal factors also play a significant role.
Explore More Air Quality Data
Extra Protection for San Francisco Homes
Air quality in San Francisco is moderate (AQI 59), 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.
Compare top-rated True-HEPA purifiers:
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