Hourly Weather | Today Wednesday, May 20, 2026
San Marcos, California
4 PM
Sunny Weather
77°
Feels Like 81°
0
Humidity: 37%
UV Index: 5
Wind: 9 mph
5 PM
Sunny Weather
75°
Feels Like 79°
0
Humidity: 38%
UV Index: 3
Wind: 8 mph
6 PM
Cloudy Weather
75°
Feels Like 75°
0
Humidity: 40%
UV Index: 2
Wind: 7 mph
7 PM
Cloudy Weather
72°
Feels Like 72°
0
Humidity: 47%
UV Index: 1
Wind: 7 mph
8 PM
Cloudy Night
70°
Feels Like 66°
0
Humidity: 59%
UV Index: 0
Wind: 6 mph
9 PM
Cloudy Night
66°
Feels Like 64°
0
Humidity: 68%
UV Index: 0
Wind: 5 mph
10 PM
Cloudy Night
63°
Feels Like 63°
0
Humidity: 75%
UV Index: 0
Wind: 5 mph
11 PM
Cloudy Night
61°
Feels Like 61°
0
Humidity: 82%
UV Index: 0
Wind: 4 mph

Hourly Air Quality Forecast - AQI (US EPA)

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

Pollutant Concentrations:

  • PM2.5: 10.63 µg/m³
  • PM10: 23.81 µg/m³
  • O3: 0.052 ppm
  • NO2: 0.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 10.48 µg/m³
  • PM10: 24.07 µg/m³
  • O3: 0.052 ppm
  • NO2: 0.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 10.31 µg/m³
  • PM10: 24.3 µg/m³
  • O3: 0.052 ppm
  • NO2: 0.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 10.12 µg/m³
  • PM10: 24.42 µg/m³
  • O3: 0.051 ppm
  • NO2: 0.3 ppb
  • SO2: 0.3 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 10 µg/m³
  • PM10: 24.5 µg/m³
  • O3: 0.051 ppm
  • NO2: 0.4 ppb
  • SO2: 0.3 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 9.93 µg/m³
  • PM10: 24.36 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.4 ppb
  • SO2: 0.3 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 9.92 µg/m³
  • PM10: 24.28 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.4 ppb
  • SO2: 0.3 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 9.9 µg/m³
  • PM10: 24.34 µg/m³
  • O3: 0.049 ppm
  • NO2: 0.4 ppb
  • SO2: 0.3 ppb
  • CO: 0.11 ppm

Health Recommendations:

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