What is the air quality trend in Thunder Bay?

Over the past 10 days, Thunder Bay had an average AQI of 101 based on station measurements. The worst day was 2026-07-18 with AQI 255.

How is Thunder Bay air quality measured?

Air quality in Thunder Bay 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 Thunder Bay, Canada

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

Historical PM2.5 and AQI trend from monitoring stations near Thunder Bay, Canada.

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

76h

PM2.5 Station

76h · 1 station

Temperature GFS model

56pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-07-21	26	25–26	6.1 µg/m³	2h	1
2026-07-20	120	57–168	50.5 µg/m³	6h	1
2026-07-19	183	163–198	118.0 µg/m³	4h	1
2026-07-18	255	173–325	201.3 µg/m³	4h	1
2026-07-17	202	199–204	151.0 µg/m³	2h	1
2026-07-12	40	34–46	9.5 µg/m³	7h	1
2026-07-11	52	46–57	13.0 µg/m³	14h	1
2026-07-10	51	38–68	13.1 µg/m³	15h	1
2026-07-09	47	38–53	11.5 µg/m³	11h	1
2026-07-08	39	25–50	9.3 µg/m³	11h	1

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