Hourly Weather | Today Friday, September 18, 2026
San Marcos, California
9 PM
Cloudy Night
66°
Feels Like 64°
0
Humidity: 82%
UV Index: 0
Wind: 5 mph
10 PM
Cloudy Night
64°
Feels Like 64°
0
Humidity: 87%
UV Index: 0
Wind: 4 mph
11 PM
Cloudy Night
64°
Feels Like 64°
0
Humidity: 88%
UV Index: 0
Wind: 4 mph

Hourly Air Quality Forecast - AQI (US EPA)

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

Pollutant Concentrations:

  • PM2.5: 5.9 µg/m³
  • PM10: 17.55 µg/m³
  • O3: 0.047 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 6.32 µg/m³
  • PM10: 18.59 µg/m³
  • O3: 0.047 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.13 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 6.67 µg/m³
  • PM10: 19.45 µg/m³
  • O3: 0.048 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.13 ppm

Health Recommendations:

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