What is the air quality trend in St. Catharines?

Over the past 15 days, St. Catharines had an average AQI of 40 based on station measurements. The worst day was 2026-05-21 with AQI 54.

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

333h

PM2.5 Station

333h · 4 stations

Temperature GFS model

56pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-05-30	36	19–69	9.5 µg/m³	10h	8
2026-05-29	42	14–187	14.5 µg/m³	24h	8
2026-05-28	29	10–66	7.1 µg/m³	24h	8
2026-05-27	45	18–176	14.2 µg/m³	24h	8
2026-05-26	28	14–50	6.7 µg/m³	24h	7
2026-05-25	42	14–160	12.2 µg/m³	24h	8
2026-05-24	38	14–72	9.9 µg/m³	24h	8
2026-05-23	49	15–176	15.6 µg/m³	24h	8
2026-05-22	30	13–71	7.5 µg/m³	24h	8
2026-05-21	54	15–151	15.8 µg/m³	24h	9
2026-05-20	53	15–192	18.5 µg/m³	24h	9
2026-05-19	42	18–76	10.7 µg/m³	24h	8
2026-05-18	35	14–57	8.4 µg/m³	24h	7
2026-05-17	34	12–71	8.4 µg/m³	23h	6
2026-05-16	45	15–116	13.1 µg/m³	12h	8

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