Hourly Weather | Today Tuesday, July 21, 2026
Active Weather Warnings
St. Peters, Missouri
3 AM
Cloudy Night
79°
Feels Like 88°
34
Humidity: 87%
UV Index: 0
Wind: 7 mph
4 AM
Cloudy Night
79°
Feels Like 86°
37
Humidity: 88%
UV Index: 0
Wind: 7 mph
5 AM
Cloudy Night
79°
Feels Like 86°
47
Humidity: 90%
UV Index: 0
Wind: 7 mph
6 AM
Sunny with a Chance of Thunderstorms
77°
Feels Like 82°
51
Humidity: 91%
UV Index: 0
Wind: 7 mph
7 AM
Cloudy Weather
79°
Feels Like 88°
47
Humidity: 86%
UV Index: 1
Wind: 7 mph
8 AM
Cloudy Weather
82°
Feels Like 91°
43
Humidity: 79%
UV Index: 2
Wind: 8 mph
9 AM
Cloudy Weather
84°
Feels Like 95°
47
Humidity: 75%
UV Index: 3
Wind: 8 mph
10 AM
Sunny with a Chance of Thunderstorms
86°
Feels Like 97°
51
Humidity: 72%
UV Index: 5
Wind: 9 mph
11 AM
Cloudy Weather
90°
Feels Like 102°
40
Humidity: 62%
UV Index: 7
Wind: 9 mph
12 PM
Cloudy Weather
91°
Feels Like 104°
34
Humidity: 54%
UV Index: 9
Wind: 9 mph
1 PM
Cloudy Weather
93°
Feels Like 104°
29
Humidity: 48%
UV Index: 11
Wind: 9 mph
2 PM
Cloudy Weather
93°
Feels Like 102°
20
Humidity: 44%
UV Index: 9
Wind: 11 mph
3 PM
Cloudy Weather
95°
Feels Like 100°
20
Humidity: 40%
UV Index: 7
Wind: 11 mph
4 PM
Cloudy Weather
93°
Feels Like 97°
20
Humidity: 40%
UV Index: 5
Wind: 11 mph
5 PM
Cloudy Weather
91°
Feels Like 93°
20
Humidity: 42%
UV Index: 3
Wind: 12 mph
6 PM
Cloudy Weather
90°
Feels Like 90°
20
Humidity: 46%
UV Index: 2
Wind: 11 mph
7 PM
Cloudy Weather
86°
Feels Like 86°
13
Humidity: 51%
UV Index: 1
Wind: 11 mph
8 PM
Cloudy Weather
82°
Feels Like 82°
0
Humidity: 57%
UV Index: 0
Wind: 9 mph
9 PM
Cloudy Night
81°
Feels Like 81°
0
Humidity: 63%
UV Index: 0
Wind: 8 mph
10 PM
Cloudy Night
79°
Feels Like 79°
0
Humidity: 68%
UV Index: 0
Wind: 7 mph
11 PM
Cloudy Night
75°
Feels Like 75°
0
Humidity: 74%
UV Index: 0
Wind: 7 mph

Hourly Air Quality Forecast - AQI (US EPA)

3 AM
13 AQI
Good air quality Dominant pollutant: PM2.5
Details

Pollutant Concentrations:

  • PM2.5: 3.17 µg/m³
  • PM10: 3.81 µg/m³
  • O3: 0.014 ppm
  • NO2: 0.7 ppb
  • SO2: 0 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

4 AM
14 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3.16 µg/m³
  • PM10: 3.86 µg/m³
  • O3: 0.015 ppm
  • NO2: 0.6 ppb
  • SO2: 0 ppb
  • CO: 0.08 ppm

Health Recommendations:

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

5 AM
15 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3 µg/m³
  • PM10: 3.74 µg/m³
  • O3: 0.016 ppm
  • NO2: 0.6 ppb
  • SO2: 0 ppb
  • CO: 0.08 ppm

Health Recommendations:

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

6 AM
15 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.85 µg/m³
  • PM10: 3.59 µg/m³
  • O3: 0.017 ppm
  • NO2: 0.6 ppb
  • SO2: 0.1 ppb
  • CO: 0.08 ppm

Health Recommendations:

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

7 AM
16 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.86 µg/m³
  • PM10: 3.58 µg/m³
  • O3: 0.017 ppm
  • NO2: 0.7 ppb
  • SO2: 0.1 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

8 AM
16 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.99 µg/m³
  • PM10: 3.7 µg/m³
  • O3: 0.018 ppm
  • NO2: 0.8 ppb
  • SO2: 0.1 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

9 AM
18 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3.2 µg/m³
  • PM10: 3.89 µg/m³
  • O3: 0.020 ppm
  • NO2: 0.8 ppb
  • SO2: 0.1 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

10 AM
24 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3.46 µg/m³
  • PM10: 4.15 µg/m³
  • O3: 0.025 ppm
  • NO2: 0.6 ppb
  • SO2: 0.2 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

11 AM
34 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3.38 µg/m³
  • PM10: 4.02 µg/m³
  • O3: 0.037 ppm
  • NO2: 0.3 ppb
  • SO2: 0.4 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.34 µg/m³
  • PM10: 3.93 µg/m³
  • O3: 0.038 ppm
  • NO2: 0.2 ppb
  • SO2: 0.4 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.46 µg/m³
  • PM10: 4.02 µg/m³
  • O3: 0.039 ppm
  • NO2: 0.2 ppb
  • SO2: 0.4 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.43 µg/m³
  • PM10: 3.93 µg/m³
  • O3: 0.039 ppm
  • NO2: 0.2 ppb
  • SO2: 0.4 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.27 µg/m³
  • PM10: 3.71 µg/m³
  • O3: 0.039 ppm
  • NO2: 0.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.21 µg/m³
  • PM10: 3.59 µg/m³
  • O3: 0.039 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.4 µg/m³
  • PM10: 3.73 µg/m³
  • O3: 0.039 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.82 µg/m³
  • PM10: 4.13 µg/m³
  • O3: 0.040 ppm
  • NO2: 0.3 ppb
  • SO2: 0.2 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 4.27 µg/m³
  • PM10: 4.54 µg/m³
  • O3: 0.041 ppm
  • NO2: 0.4 ppb
  • SO2: 0.2 ppb
  • CO: 0.10 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: 4.77 µg/m³
  • PM10: 5 µg/m³
  • O3: 0.041 ppm
  • NO2: 0.6 ppb
  • SO2: 0.2 ppb
  • CO: 0.10 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: 5.39 µg/m³
  • PM10: 5.58 µg/m³
  • O3: 0.039 ppm
  • NO2: 0.7 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 6.04 µg/m³
  • PM10: 6.19 µg/m³
  • O3: 0.038 ppm
  • NO2: 0.8 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 6.35 µg/m³
  • PM10: 6.47 µg/m³
  • O3: 0.037 ppm
  • NO2: 0.8 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

Weather Alerts and Warnings for St. Peters

Moderate Expected Likely

Heat Advisory

Heat Advisory issued July 20 at 8:23PM CDT until July 21 at 7:00PM CDT by NWS St Louis MO
Jul 20, 8:23 PM Jul 21, 7:00 PM
WHAT: Heat index values up to 109.

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

WHEN: Until 7 PM CDT Tuesday.

IMPACTS: Hot temperatures and high humidity may cause heat
illnesses.
+ Read More
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: Jul 21, 1:33 AM Source: NWS Alert