San Francisco Air Quality Index (AQI) Today - Live Pollution Data
Real-time air quality monitoring for San Francisco, California. Get current AQI levels, health recommendations, pollution forecasts, and safety guidance for San Francisco.
Current Pollutant Levels:
San Francisco 4-Day Air Quality Forecast
San Francisco 30-Day Air Quality History
San Francisco Air Quality Data & Environmental Insights
Understanding San Francisco Air Quality
The air quality in San Francisco, California varies throughout the day and season. Our real-time monitoring system tracks PM2.5, PM10, ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO) levels to provide accurate AQI readings for San Francisco.
Air quality monitoring in San Francisco helps residents make informed decisions about outdoor activities. Weather patterns, local emissions, and seasonal factors all influence daily air quality readings.
Health Recommendations for San Francisco Residents
Good Air Quality (0-50)
Air quality is satisfactory in San Francisco. Perfect for all outdoor activities including jogging, cycling, and sports.
Moderate Air Quality (51-100)
Sensitive individuals in San Francisco should consider limiting prolonged outdoor exertion, especially those with asthma or heart conditions.
Unhealthy Air Quality (101+)
When San Francisco air quality reaches unhealthy levels, everyone should reduce outdoor activities and consider wearing N95 masks outdoors.
Air Pollution Sources in San Francisco
Transportation
Vehicle emissions are a major contributor to urban air pollution
Local Industry
Manufacturing and industrial processes affect air quality
Weather Patterns
Wind, temperature, and humidity influence pollution dispersion
Regional Sources
Pollution can travel from neighboring areas
Best Times for Outdoor Activities in San Francisco
Daily Patterns
In San Francisco, air quality is typically best in early morning (6-8 AM) and late evening (8-10 PM) when traffic is lighter and atmospheric conditions favor pollution dispersion.
Seasonal Trends
Monitor San Francisco AQI regularly as seasonal weather patterns can significantly impact air quality. Spring and summer often provide better conditions for outdoor exercise.
San Francisco Metropolitan Area Facts
Frequently Asked Questions About San Francisco Air Quality
Is San Francisco air quality safe today?
The current air quality in San Francisco will be displayed above with real-time data. Check the AQI value and color coding to determine if it's safe for outdoor activities.
What time of day is air quality best in San Francisco?
Generally, air quality tends to be better in early morning hours (4-7 AM) and late evening (after 9 PM) when traffic is lighter. However, this can vary based on local conditions and weather patterns in San Francisco.
What causes air pollution in San Francisco?
Common sources of air pollution include vehicle emissions, industrial activities, construction dust, and seasonal factors. The specific mix varies by location and time of year.
How accurate is San Francisco AQI data?
Our data comes from official monitoring stations and satellite observations, updated every hour. We use the same data sources as government agencies to ensure accuracy.
Recommended Air Purifier for San Francisco
Health Recommendations for San Francisco Residents
San Francisco Outdoor Exercise Locations by Air Quality
Best Air Quality Spots
- Presidio National Park (extensive forest with ocean access)
- Golden Gate Park (large urban forest and gardens)
- Twin Peaks (elevated natural area with bay views)
- Lands End (coastal preserve with ocean exposure)
Moderate Air Quality Areas
- Downtown areas during off-peak hours
- Suburban parks and trails
- Residential neighborhoods
Higher Pollution Risk
- Major highway corridors
- Industrial areas
- Airport vicinity
- Downtown during rush hours
San Francisco Air Quality vs Nearby Cities
How does San Francisco's air quality compare to nearby cities within 300km?
San Francisco's Regional Air Quality Context:
- Real-time comparison with cities within 300km radius
- Regional weather patterns affect air quality similarly across nearby cities
- Local pollution sources and geography create unique conditions
- Monitor regional trends to understand broader air quality patterns
San Francisco Air Quality FAQ
What is the typical AQI range in San Francisco?
San Francisco enjoys good air quality with AQI typically ranging from 30-65, benefiting from its unique peninsula location with constant ocean breezes that naturally disperse pollutants and provide clean marine air.
The annual average AQI of 45 reflects the natural advantages of ocean proximity and topographic air circulation combined with strong environmental policies, though occasional wildfire smoke events can create temporary severe pollution episodes.
Air quality varies significantly during wildfire season when regional smoke transport can overwhelm the natural ventilation advantages, while normal conditions benefit from some of the most favorable geography for air quality in any major U.S. city.
When is San Francisco air quality worst?
Wildfire season (July-October) can create catastrophic air quality episodes, raising AQI from typical 40-50 to 200-500+ when smoke from regional fires overwhelms the natural ocean breeze ventilation system.
Rush hour periods along Highway 101, I-280, and bridge approaches create moderate pollution concentrations, raising AQI from 45 to 60-85 during peak commuting when traffic density is highest.
Atmospheric inversions during certain weather patterns can trap pollution against the coastal mountains, raising AQI from 40 to 70-120 when normal ocean breeze patterns are disrupted.
Regional pollution transport during offshore wind events can bring Central Valley smog westward, raising AQI from 45 to 70-110 when inland pollution reaches the coast.
How do seasonal changes affect San Francisco's air quality?
Summer brings variable air quality with AQI typically 40-70 during normal conditions, but wildfire season can create severe episodes with AQI reaching 200-400+ when regional smoke overwhelms natural ventilation.
Fall continues wildfire risk while offering some of the best air quality during clear periods, with AQI usually 35-65 when ocean breezes are strong and no fires are active.
Winter provides excellent air quality with AQI typically 30-55, benefiting from strong Pacific storm systems that clear the atmosphere and minimal wildfire risk.
Spring offers excellent conditions with AQI 30-60 as ocean breezes are consistent and wildfire season has not yet begun, providing optimal natural air circulation.
How does San Francisco compare to other cities?
San Francisco enjoys some of the best natural air quality advantages of any major U.S. city due to its peninsula location with constant ocean breezes and topographic air circulation patterns.
Among California cities, San Francisco benefits from superior natural ventilation compared to inland areas, though shares regional wildfire smoke risks that can temporarily create severe pollution episodes.
The city demonstrates how geographic advantages combined with strong environmental policies can maintain good air quality in a dense urban environment, serving as a model for coastal urban air quality management.