Today | Weather | Wednesday, May 20, 2026

Weather in St. Charles, Missouri

04:51 PM
Now
Cloudy Weather
68° F
Feels Like 66°
Precipitation 20 %
Wind 8 mph
UV Index (0 - 11+) 2
Humidity 57 %
Today
Rainy Weather
Day 68°
Night 54°
Precipitation 55 %
Wind 8 mph
UV Index (0 - 11+) 4

St. Charles Weather Forecast Updated

Last updated on

Air Quality in St. Charles

NOW
34 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 4.1 µg/m³
PM10 4.45 µg/m³
O3 0.036 ppm
NO2 0.6 ppb
SO2 0.9 ppb
CO 0.11 ppm
NH3 1.15 µg/m³
NO 0.17 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.54.1 µg/m³
PM104.45 µg/m³
O371.16 µg/m³
NO21.21 µg/m³
SO22.44 µg/m³
CO125.8 µg/m³
NH31.15 µg/m³
NO0.17 µg/m³