Hourly Weather | Today Tuesday, June 9, 2026
Active Weather Warnings
O'Fallon, Missouri
9 PM
Cloudy Night
84°
Feels Like 93°
6
Humidity: 76%
UV Index: 0
Wind: 6 mph
10 PM
Cloudy Night
81°
Feels Like 90°
6
Humidity: 81%
UV Index: 0
Wind: 5 mph
11 PM
Cloudy Night
79°
Feels Like 88°
6
Humidity: 85%
UV Index: 0
Wind: 6 mph

Hourly Air Quality Forecast - AQI (US EPA)

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

Pollutant Concentrations:

  • PM2.5: 2.23 µg/m³
  • PM10: 2.92 µg/m³
  • O3: 0.021 ppm
  • NO2: 0.4 ppb
  • SO2: 0 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.26 µg/m³
  • PM10: 3.03 µg/m³
  • O3: 0.020 ppm
  • NO2: 0.4 ppb
  • SO2: 0 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.24 µg/m³
  • PM10: 3.07 µg/m³
  • O3: 0.020 ppm
  • NO2: 0.4 ppb
  • SO2: 0 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

Weather Alerts and Warnings for O'Fallon

Moderate Expected Likely

Heat Advisory

Heat Advisory issued June 9 at 2:50PM CDT until June 9 at 10:00PM CDT by NWS St Louis MO
Jun 9, 2:50 PM Jun 9, 10:00 PM
WHAT: Heat index values up to 105.

WHERE: Portions of southwest Illinois and central, east central,
and southeast Missouri.

WHEN: Until 10 PM CDT this evening.

IMPACTS: Hot temperatures and high humidity may cause heat
illnesses.
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Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. Take extra precautions if you work or spend time outside. When possible reschedule strenuous activities to early morning or evening. Know the signs and symptoms of heat exhaustion and heat stroke. Wear lightweight and loose fitting clothing when possible. To reduce risk during outdoor work, the Occupational Safety and Health Administration recommends scheduling frequent rest breaks in shaded or air conditioned environments. Anyone overcome by heat should be moved to a cool and shaded location. Heat stroke is an emergency! Call 9 1 1.
Updated: Jun 9, 7:51 PM Source: NWS Alert