What is the air quality trend in St. Catharines?

Over the past 15 days, St. Catharines had an average AQI of 41 based on station measurements. The worst day was 2026-05-25 with AQI 57.

How is St. Catharines air quality measured?

Air quality in St. Catharines 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 St. Catharines, Canada

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

Historical PM2.5 and AQI trend from monitoring stations near St. Catharines, Canada.

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

334h

PM2.5 Station

334h · 2 stations

Temperature GFS model

56pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-05-30	43	10–100	12.3 µg/m³	12h	7
2026-05-29	42	16–157	12.3 µg/m³	24h	8
2026-05-28	28	10–76	7.0 µg/m³	24h	8
2026-05-27	45	13–175	14.2 µg/m³	24h	8
2026-05-26	29	18–50	6.9 µg/m³	24h	7
2026-05-25	57	17–318	24.6 µg/m³	24h	8
2026-05-24	39	13–75	10.1 µg/m³	24h	8
2026-05-23	47	15–169	14.6 µg/m³	24h	9
2026-05-22	34	12–69	8.6 µg/m³	24h	8
2026-05-21	51	14–160	14.8 µg/m³	24h	8
2026-05-20	55	13–193	19.1 µg/m³	24h	9
2026-05-19	44	16–86	11.7 µg/m³	24h	7
2026-05-18	39	24–56	9.5 µg/m³	24h	7
2026-05-17	36	23–71	9.1 µg/m³	24h	5
2026-05-16	37	19–107	10.2 µg/m³	10h	9

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