Thunder Bay Seasonal Pollution
Thunder Bay usually records its highest OpenAQ-derived EPA AQI in July and its cleanest month in November. The page uses OpenAQ-derived daily history for 2 mapped monitoring locations in Ontario, Canada.
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Average EPA AQI
27
Rank 97 of 158 cities by average AQI
PM2.5
5.6
ug/m3 annualized city average
Seasonality
July
Cleanest: November
Health indicator
0.3
cigarette-equivalent per day
Yearly EPA AQI trend
Seasonal EPA AQI heatmap
JanFebMarAprMayJunJulAugSepOctNovDec
Thunder Bay
25
31
26
22
27
31
48
46
31
14
12
16
What this seasonality page measures
Find each city's worst and cleanest months from daily OpenAQ-derived EPA AQI.
For Thunder Bay, the current global analytics build covers 358 daily rows from 2024-01-01 to 2025-01-01. The calculations normalize PM2.5 and PM10 observations into US EPA AQI bands so country, city, and tool pages use one consistent method.