What is the air quality trend in Redwood City?

Over the past 3 days, Redwood City had an average AQI of 21 based on station measurements. The worst day was 2026-09-05 with AQI 25.

How is Redwood City air quality measured?

Air quality in Redwood City is measured by ground-level monitoring stations that report PM2.5 and PM10 concentrations hourly. CERNS.IO aggregates readings from nearby stations and converts PM2.5 to the US EPA Air Quality Index (AQI) scale.

Air Quality History for Redwood City, United States

Name: Redwood City Air Quality History
Creator: CERNS.IO
License: https://creativecommons.org/licenses/by/4.0/

Historical PM2.5 and AQI trend from monitoring stations near Redwood City, United States.

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

45h

PM2.5 Station

45h · 108 stations

Temperature GFS model

8pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	PM10 avg	Hours	Stations
2026-09-05	25	24–27	5.9 µg/m³	3.8	20h	106
2026-09-04	22	13–28	5.3 µg/m³	3.4	24h	108
2026-09-03	18	18–18	4.3 µg/m³	3.9	1h	106

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