Hourly Weather | Today Tuesday, July 21, 2026
Active Weather Warnings
Castle Rock, Colorado
3 AM
Cloudy Night
70°
Feels Like 66°
0
Humidity: 52%
UV Index: 0
Wind: 8 mph
4 AM
Cloudy Night
66°
Feels Like 64°
0
Humidity: 56%
UV Index: 0
Wind: 8 mph
5 AM
Cloudy Night
66°
Feels Like 63°
0
Humidity: 61%
UV Index: 0
Wind: 8 mph
6 AM
Cloudy Weather
64°
Feels Like 63°
0
Humidity: 66%
UV Index: 0
Wind: 8 mph
7 AM
Cloudy Weather
66°
Feels Like 66°
0
Humidity: 61%
UV Index: 1
Wind: 8 mph
8 AM
Cloudy Weather
72°
Feels Like 72°
0
Humidity: 52%
UV Index: 2
Wind: 9 mph
9 AM
Cloudy Weather
75°
Feels Like 79°
0
Humidity: 45%
UV Index: 4
Wind: 9 mph
10 AM
Cloudy Weather
81°
Feels Like 82°
0
Humidity: 40%
UV Index: 5
Wind: 9 mph
11 AM
Cloudy Weather
82°
Feels Like 90°
0
Humidity: 36%
UV Index: 8
Wind: 8 mph
12 PM
Cloudy Weather
86°
Feels Like 93°
0
Humidity: 32%
UV Index: 10
Wind: 8 mph
1 PM
Cloudy Weather
90°
Feels Like 95°
1
Humidity: 28%
UV Index: 11
Wind: 9 mph
2 PM
Cloudy Weather
90°
Feels Like 93°
43
Humidity: 26%
UV Index: 9
Wind: 13 mph
3 PM
Cloudy Weather
91°
Feels Like 93°
47
Humidity: 24%
UV Index: 5
Wind: 14 mph
4 PM
Sunny with a Chance of Thunderstorms
90°
Feels Like 84°
51
Humidity: 33%
UV Index: 2
Wind: 14 mph
5 PM
Cloudy Weather
88°
Feels Like 84°
19
Humidity: 33%
UV Index: 2
Wind: 15 mph
6 PM
Cloudy Weather
88°
Feels Like 86°
15
Humidity: 30%
UV Index: 2
Wind: 15 mph
7 PM
Cloudy Weather
86°
Feels Like 82°
19
Humidity: 29%
UV Index: 1
Wind: 14 mph
8 PM
Sunny with a Chance of Thunderstorms
81°
Feels Like 73°
64
Humidity: 41%
UV Index: 0
Wind: 14 mph
9 PM
Cloudy Night
77°
Feels Like 73°
49
Humidity: 48%
UV Index: 0
Wind: 14 mph
10 PM
Stormy Weather
75°
Feels Like 68°
64
Humidity: 52%
UV Index: 0
Wind: 14 mph
11 PM
Cloudy Night
72°
Feels Like 70°
40
Humidity: 57%
UV Index: 0
Wind: 13 mph

Hourly Air Quality Forecast - AQI (US EPA)

3 AM
27 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.28 µg/m³
  • PM10: 2.98 µg/m³
  • O3: 0.029 ppm
  • NO2: 1.4 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.25 µg/m³
  • PM10: 2.95 µg/m³
  • O3: 0.028 ppm
  • NO2: 1.5 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.28 µg/m³
  • PM10: 2.97 µg/m³
  • O3: 0.028 ppm
  • NO2: 1.6 ppb
  • SO2: 0.1 ppb
  • CO: 0.08 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.34 µg/m³
  • PM10: 3.03 µg/m³
  • O3: 0.028 ppm
  • NO2: 1.7 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
25 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.38 µg/m³
  • PM10: 3.06 µg/m³
  • O3: 0.027 ppm
  • NO2: 1.9 ppb
  • SO2: 0 ppb
  • CO: 0.08 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.4 µg/m³
  • PM10: 3.08 µg/m³
  • O3: 0.026 ppm
  • NO2: 1.9 ppb
  • SO2: 0 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.45 µg/m³
  • PM10: 3.15 µg/m³
  • O3: 0.027 ppm
  • NO2: 1.7 ppb
  • SO2: 0 ppb
  • CO: 0.09 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.11 µg/m³
  • PM10: 2.98 µg/m³
  • O3: 0.039 ppm
  • NO2: 0.3 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 1.93 µg/m³
  • PM10: 2.72 µg/m³
  • O3: 0.040 ppm
  • NO2: 0.1 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.03 µg/m³
  • PM10: 2.84 µg/m³
  • O3: 0.041 ppm
  • NO2: 0.1 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.31 µg/m³
  • PM10: 3.06 µg/m³
  • O3: 0.042 ppm
  • NO2: 0.1 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.71 µg/m³
  • PM10: 3.36 µg/m³
  • O3: 0.044 ppm
  • NO2: 0.2 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.28 µg/m³
  • PM10: 3.9 µg/m³
  • O3: 0.045 ppm
  • NO2: 0.2 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.71 µg/m³
  • PM10: 4.33 µg/m³
  • O3: 0.046 ppm
  • NO2: 0.2 ppb
  • SO2: 0.1 ppb
  • CO: 0.07 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.86 µg/m³
  • PM10: 4.48 µg/m³
  • O3: 0.046 ppm
  • NO2: 0.3 ppb
  • SO2: 0.1 ppb
  • CO: 0.08 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.75 µg/m³
  • PM10: 4.36 µg/m³
  • O3: 0.045 ppm
  • NO2: 0.4 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 PM
40 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3.54 µg/m³
  • PM10: 4.09 µg/m³
  • O3: 0.043 ppm
  • NO2: 0.5 ppb
  • SO2: 0.1 ppb
  • CO: 0.08 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.32 µg/m³
  • PM10: 3.79 µg/m³
  • O3: 0.042 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.

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

Pollutant Concentrations:

  • PM2.5: 3.14 µg/m³
  • PM10: 3.57 µg/m³
  • O3: 0.041 ppm
  • NO2: 0.7 ppb
  • SO2: 0.1 ppb
  • CO: 0.08 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: 2.97 µg/m³
  • PM10: 3.33 µg/m³
  • O3: 0.038 ppm
  • NO2: 0.9 ppb
  • SO2: 0.1 ppb
  • CO: 0.08 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 2.9 µg/m³
  • PM10: 3.22 µg/m³
  • O3: 0.034 ppm
  • NO2: 1.1 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 Castle Rock

Air Quality Alert

Air Quality Alert issued July 20 at 4:10PM MDT by NWS Denver CO
Jul 20, 4:10 PM Jul 21, 4:00 PM
The Colorado Department of Public Health and Environment has
issued the following...

WHAT...Ozone Action Day Alert.

WHERE...Douglas, Jefferson, Denver, western Arapahoe, western
Adams, Broomfield, Boulder, Larimer, and Weld Counties

WHEN...400 PM Monday July 20 to 400 PM Tuesday July 21

IMPACTS...Ozone Action Day Alert is now in effect for the Front
Range Urban Corridor. Hot and stagnant weather conditions will
result in ozone concentrations reaching the Unhealthy for
Sensitive Groups category both Monday and Tuesday during the
afternoon and evening hours. For Colorado air quality conditions,
forecasts, and advisories, visit:
https://www.colorado.gov/airquality/colorado_summary.aspx If
possible, please help us reduce ozone pollution by limiting
driving gas and diesel-powered vehicles until at least 4 p.m.
Tuesday, July 21, 2026. Colorado is also addressing ozone
pollution through state policies. For more information about
health impacts and how ozone pollution forms in Colorado, visit:
https://cdphe.colorado.gov/ozone- pollution-and-your-health

HEALTH INFORMATION...Increasing likelihood of respiratory symptoms
and breathing discomfort in active children and adults and people
with lung disease, such as asthma. Active children and adults, and
people with lung disease, such as asthma, should reduce prolonged
or heavy outdoor exertion.
Updated: Jul 21, 1:44 AM Source: NWS Alert