What is the air quality trend in Seattle?

Over the past 8 days, Seattle had an average AQI of 12 based on station measurements. The worst day was 2026-05-24 with AQI 17.

How is Seattle air quality measured?

Air quality in Seattle 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 Seattle, United States

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

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

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

167h

PM2.5 Station

167h · 1 station

Temperature GFS model

28pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-05-28	12	8–21	2.9 µg/m³	23h	1
2026-05-27	8	8–12	2.1 µg/m³	24h	1
2026-05-26	9	8–12	2.2 µg/m³	24h	1
2026-05-25	12	8–21	2.9 µg/m³	24h	1
2026-05-24	17	12–21	4.0 µg/m³	24h	1
2026-05-23	13	8–21	3.1 µg/m³	24h	1
2026-05-22	16	8–22	3.8 µg/m³	23h	2
2026-05-21	12	12–12	3.0 µg/m³	1h	1

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