Hourly Weather | Today Wednesday, March 18, 2026
O'Fallon, Missouri
1 PM
Cloudy Weather
55°
Feels Like 55°
0
Humidity: 45%
UV Index: 5
Wind: 14 mph
2 PM
Cloudy Weather
61°
Feels Like 63°
0
Humidity: 41%
UV Index: 5
Wind: 9 mph
3 PM
Cloudy Weather
63°
Feels Like 64°
0
Humidity: 40%
UV Index: 4
Wind: 9 mph
4 PM
Cloudy Weather
64°
Feels Like 64°
0
Humidity: 39%
UV Index: 3
Wind: 9 mph
5 PM
Cloudy Weather
63°
Feels Like 64°
0
Humidity: 42%
UV Index: 2
Wind: 8 mph
6 PM
Cloudy Weather
61°
Feels Like 61°
0
Humidity: 48%
UV Index: 1
Wind: 6 mph
7 PM
Cloudy Weather
57°
Feels Like 57°
0
Humidity: 54%
UV Index: 0
Wind: 5 mph
8 PM
Cloudy Night
59°
Feels Like 57°
0
Humidity: 50%
UV Index: 0
Wind: 5 mph
9 PM
Cloudy Night
55°
Feels Like 55°
0
Humidity: 56%
UV Index: 0
Wind: 5 mph
10 PM
Cloudy Night
52°
Feels Like 52°
0
Humidity: 62%
UV Index: 0
Wind: 5 mph
11 PM
Cloudy Night
50°
Feels Like 48°
0
Humidity: 69%
UV Index: 0
Wind: 5 mph

Hourly Air Quality Forecast - AQI (US EPA)

1 PM
52 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.09 µg/m³
  • PM10: 5.66 µg/m³
  • O3: 0.055 ppm
  • NO2: 0.5 ppb
  • SO2: 0.5 ppb
  • CO: 0.13 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

2 PM
64 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.49 µg/m³
  • PM10: 6.12 µg/m³
  • O3: 0.058 ppm
  • NO2: 0.4 ppb
  • SO2: 0.5 ppb
  • CO: 0.13 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

3 PM
69 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.85 µg/m³
  • PM10: 6.46 µg/m³
  • O3: 0.060 ppm
  • NO2: 0.4 ppb
  • SO2: 0.5 ppb
  • CO: 0.13 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

4 PM
71 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 5.08 µg/m³
  • PM10: 6.67 µg/m³
  • O3: 0.061 ppm
  • NO2: 0.4 ppb
  • SO2: 0.5 ppb
  • CO: 0.13 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

5 PM
59 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 5.39 µg/m³
  • PM10: 6.9 µg/m³
  • O3: 0.057 ppm
  • NO2: 0.7 ppb
  • SO2: 0.4 ppb
  • CO: 0.13 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

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

Pollutant Concentrations:

  • PM2.5: 5.7 µg/m³
  • PM10: 7.14 µg/m³
  • O3: 0.050 ppm
  • NO2: 1.6 ppb
  • SO2: 0.3 ppb
  • CO: 0.15 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 5.89 µg/m³
  • PM10: 7.35 µg/m³
  • O3: 0.044 ppm
  • NO2: 2.7 ppb
  • SO2: 0.2 ppb
  • CO: 0.16 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 6.04 µg/m³
  • PM10: 7.52 µg/m³
  • O3: 0.041 ppm
  • NO2: 3.3 ppb
  • SO2: 0.2 ppb
  • CO: 0.17 ppm

Health Recommendations:

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

9 PM
36 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 6.24 µg/m³
  • PM10: 7.71 µg/m³
  • O3: 0.039 ppm
  • NO2: 3.2 ppb
  • SO2: 0.1 ppb
  • CO: 0.17 ppm

Health Recommendations:

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

10 PM
36 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 6.47 µg/m³
  • PM10: 7.91 µg/m³
  • O3: 0.038 ppm
  • NO2: 2.8 ppb
  • SO2: 0.1 ppb
  • CO: 0.17 ppm

Health Recommendations:

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

11 PM
38 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 6.58 µg/m³
  • PM10: 8.04 µg/m³
  • O3: 0.041 ppm
  • NO2: 2 ppb
  • SO2: 0.1 ppb
  • CO: 0.16 ppm

Health Recommendations:

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