What is the air quality trend in Saint Charles?

Over the past 3 days, Saint Charles had an average AQI of 46 based on station measurements. The worst day was 2026-07-20 with AQI 66.

How is Saint Charles air quality measured?

Air quality in Saint Charles 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 Saint Charles, United States

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

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

Current AQI
Good Station

48 Hours 7 Days 14 Days 20 Days

CSV JSON

Air Quality Index Station

46h

PM2.5 Station

46h · 31 stations

Temperature GFS model

8pt

Precipitation GFS model

mm/day

Daily Summary Station

Date	AQI	Range	PM2.5 avg	Hours	Stations
2026-07-22	20	16–26	4.9 µg/m³	5h	29
2026-07-21	53	28–75	14.7 µg/m³	24h	28
2026-07-20	66	51–79	19.4 µg/m³	17h	28

Back to Saint Charles Air Quality