Hourly Weather | Today Saturday, May 16, 2026
San Mateo, California
12 PM
Cloudy Weather
64°
Feels Like 66°
0
Humidity: 56%
UV Index: 9
Wind: 16 mph
1 PM
Cloudy Weather
66°
Feels Like 70°
0
Humidity: 54%
UV Index: 10
Wind: 18 mph
2 PM
Cloudy Weather
66°
Feels Like 70°
0
Humidity: 51%
UV Index: 9
Wind: 20 mph
3 PM
Cloudy Weather
66°
Feels Like 66°
0
Humidity: 52%
UV Index: 7
Wind: 22 mph
4 PM
Cloudy Weather
64°
Feels Like 63°
0
Humidity: 54%
UV Index: 5
Wind: 22 mph
5 PM
Cloudy Weather
64°
Feels Like 61°
0
Humidity: 56%
UV Index: 3
Wind: 23 mph
6 PM
Cloudy Weather
63°
Feels Like 57°
0
Humidity: 57%
UV Index: 2
Wind: 22 mph
7 PM
Cloudy Weather
61°
Feels Like 55°
0
Humidity: 61%
UV Index: 1
Wind: 21 mph
8 PM
Cloudy Weather
57°
Feels Like 52°
0
Humidity: 66%
UV Index: 0
Wind: 18 mph
9 PM
Cloudy Night
55°
Feels Like 48°
0
Humidity: 71%
UV Index: 0
Wind: 17 mph
10 PM
Cloudy Night
54°
Feels Like 46°
0
Humidity: 76%
UV Index: 0
Wind: 15 mph
11 PM
Cloudy Night
54°
Feels Like 46°
0
Humidity: 76%
UV Index: 0
Wind: 14 mph

Hourly Air Quality Forecast - AQI (US EPA)

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

Pollutant Concentrations:

  • PM2.5: 3.14 µg/m³
  • PM10: 15.67 µg/m³
  • O3: 0.053 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.24 µg/m³
  • PM10: 16.28 µg/m³
  • O3: 0.053 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.35 µg/m³
  • PM10: 16.95 µg/m³
  • O3: 0.053 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.44 µg/m³
  • PM10: 17.54 µg/m³
  • O3: 0.052 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.56 µg/m³
  • PM10: 18.2 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.72 µg/m³
  • PM10: 18.96 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 3.9 µg/m³
  • PM10: 19.82 µg/m³
  • O3: 0.049 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 4.01 µg/m³
  • PM10: 20.46 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 4.06 µg/m³
  • PM10: 20.86 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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

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

Pollutant Concentrations:

  • PM2.5: 4.08 µg/m³
  • PM10: 21.12 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.2 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
46 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.12 µg/m³
  • PM10: 21.37 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.2 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
46 AQI
Good air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 4.14 µg/m³
  • PM10: 21.54 µg/m³
  • O3: 0.050 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.11 ppm

Health Recommendations:

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