Hourly Weather | Today Monday, September 21, 2026
St. Charles, Missouri
2 PM
Cloudy Weather
73°
Feels Like 73°
7
Humidity: 78%
UV Index: 1
Wind: 7 mph
3 PM
Cloudy Weather
73°
Feels Like 73°
7
Humidity: 75%
UV Index: 1
Wind: 8 mph
4 PM
Cloudy Weather
73°
Feels Like 73°
7
Humidity: 76%
UV Index: 1
Wind: 8 mph
5 PM
Cloudy Weather
72°
Feels Like 72°
7
Humidity: 77%
UV Index: 1
Wind: 8 mph
6 PM
Cloudy Weather
72°
Feels Like 70°
7
Humidity: 77%
UV Index: 0
Wind: 8 mph
7 PM
Cloudy Weather
70°
Feels Like 68°
5
Humidity: 78%
UV Index: 0
Wind: 8 mph
8 PM
Cloudy Weather
70°
Feels Like 68°
0
Humidity: 82%
UV Index: 0
Wind: 8 mph
9 PM
Cloudy Weather
70°
Feels Like 66°
0
Humidity: 81%
UV Index: 0
Wind: 7 mph
10 PM
Cloudy Weather
68°
Feels Like 66°
0
Humidity: 82%
UV Index: 0
Wind: 7 mph
11 PM
Cloudy Weather
66°
Feels Like 64°
0
Humidity: 83%
UV Index: 0
Wind: 7 mph

Hourly Air Quality Forecast - AQI (US EPA)

2 PM
29 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.81 µg/m³
  • PM10: 4.88 µg/m³
  • O3: 0.031 ppm
  • NO2: 0.6 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

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

3 PM
26 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.86 µg/m³
  • PM10: 4.93 µg/m³
  • O3: 0.028 ppm
  • NO2: 0.6 ppb
  • SO2: 0.1 ppb
  • CO: 0.13 ppm

Health Recommendations:

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

4 PM
23 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.89 µg/m³
  • PM10: 4.96 µg/m³
  • O3: 0.025 ppm
  • NO2: 0.6 ppb
  • SO2: 0.1 ppb
  • CO: 0.13 ppm

Health Recommendations:

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

5 PM
21 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.82 µg/m³
  • PM10: 4.88 µg/m³
  • O3: 0.023 ppm
  • NO2: 0.7 ppb
  • SO2: 0.1 ppb
  • CO: 0.13 ppm

Health Recommendations:

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

6 PM
22 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.73 µg/m³
  • PM10: 4.79 µg/m³
  • O3: 0.023 ppm
  • NO2: 0.8 ppb
  • SO2: 0.1 ppb
  • CO: 0.13 ppm

Health Recommendations:

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

7 PM
22 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.64 µg/m³
  • PM10: 4.7 µg/m³
  • O3: 0.023 ppm
  • NO2: 0.9 ppb
  • SO2: 0.1 ppb
  • CO: 0.14 ppm

Health Recommendations:

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

8 PM
21 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.74 µg/m³
  • PM10: 4.81 µg/m³
  • O3: 0.023 ppm
  • NO2: 1 ppb
  • SO2: 0.1 ppb
  • CO: 0.14 ppm

Health Recommendations:

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

9 PM
21 AQI
Good air quality Dominant pollutant: PM2.5
Details

Pollutant Concentrations:

  • PM2.5: 5.03 µg/m³
  • PM10: 5.11 µg/m³
  • O3: 0.021 ppm
  • NO2: 1.3 ppb
  • SO2: 0.2 ppb
  • CO: 0.15 ppm

Health Recommendations:

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

10 PM
23 AQI
Good air quality Dominant pollutant: PM2.5
Details

Pollutant Concentrations:

  • PM2.5: 5.4 µg/m³
  • PM10: 5.52 µg/m³
  • O3: 0.018 ppm
  • NO2: 1.8 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

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

11 PM
24 AQI
Good air quality Dominant pollutant: PM2.5
Details

Pollutant Concentrations:

  • PM2.5: 5.85 µg/m³
  • PM10: 6.03 µg/m³
  • O3: 0.016 ppm
  • NO2: 2.4 ppb
  • SO2: 0.6 ppb
  • CO: 0.16 ppm

Health Recommendations:

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