Today | Weather | Monday, October 12, 2026

Weather in St. Charles, Missouri

08:06 PM
Now
Night
84° F
Feels Like 82°
Precipitation 0 %
Wind 9 mph
Humidity 45 %
Today
Night
Day 97°
Night 66°
Precipitation 3 %
Wind 8 mph

St. Charles Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (October 12, 2025)
Cloudy Night

Day

82°

Night

61°

Wind

7 mph

Precipitation

15 %

Air Quality in St. Charles

NOW
40 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 4.28 µg/m³
PM10 6.71 µg/m³
O3 0.043 ppm
NO2 0.6 ppb
SO2 0.1 ppb
CO 0.09 ppm
NH3 0.72 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)
PM2.5 – 4.28 µg/m³
PM10 – 6.71 µg/m³
O3 – 84.18 µg/m³
NO2 – 1.04 µg/m³
SO2 – 0.3 µg/m³
CO – 100.76 µg/m³
NH3 – 0.72 µg/m³
NO – 0 µg/m³