Today | Weather | Wednesday, March 18, 2026

Weather in St. Charles, Missouri

04:21 AM
Now
Cloudy Weather
34° F
Feels Like 25°
Precipitation 44 %
Wind 9 mph
Humidity 62 %
Today
Cloudy Weather
Day 64°
Night 43°
Precipitation 3 %
Wind 8 mph
UV Index (0 - 11+) 5

St. Charles Weather Forecast Updated

Last updated on

Air Quality in St. Charles

NOW
47 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 3.24 µg/m³
PM10 4 µg/m³
O3 0.051 ppm
NO2 0.7 ppb
SO2 0.6 ppb
CO 0.13 ppm
NH3 1.7 µg/m³
NO 0 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)
PM2.53.24 µg/m³
PM104 µg/m³
O3100.13 µg/m³
NO21.26 µg/m³
SO21.46 µg/m³
CO150.44 µg/m³
NH31.7 µg/m³
NO0 µg/m³