California note
San Mateo County smoke can arrive from far away
San Mateo County directs residents to the Bay Area AQI map for current air conditions and SMC Alert for county emergency messages on poor-air days.
Wildfire smoke can affect San Mateo County even when the fire is several states away. That applies across the hills, Coastside, and Peninsula, so distance from a visible fire is not a reliable air-quality test.
Use the Air Quality Index rather than the view from the window. AQI runs from 0 to 500, and a higher number means a greater possible health effect. The county links the Bay Area Air District’s current air-quality map for the measured conditions.
The map and the alert system have different jobs. Check the map before outdoor work, school sports, or an event. Register for SMC Alert to receive official county news and instructions during poor-air days. If the AQI is high, follow the county’s current steps for reducing exposure and any advice from your medical professional.
Smoke can shift with the wind, so check again if conditions change. A morning reading may not settle the whole day.
Where to see it
San Mateo County emergency preparedness page.
Official sources
Official pages
Reviewed July 14, 2026
Current maps, alerts, conditions, and public safety guidance.
Conditions and public guidance can change quickly. Check the current page before you act.
Connected places
Open the local directory
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