Hourly Weather | Today Sunday, April 26, 2026
San Mateo, California
9 AM
Cloudy Weather
55°
Feels Like 55°
31
Humidity: 81%
UV Index: 1
Wind: 8 mph
10 AM
Partly Sunny with Showers
57°
Feels Like 57°
31
Humidity: 73%
UV Index: 2
Wind: 8 mph
11 AM
Cloudy Weather
61°
Feels Like 61°
30
Humidity: 67%
UV Index: 3
Wind: 9 mph
12 PM
Cloudy Weather
61°
Feels Like 63°
24
Humidity: 63%
UV Index: 4
Wind: 10 mph
1 PM
Cloudy Weather
63°
Feels Like 64°
27
Humidity: 59%
UV Index: 4
Wind: 12 mph
2 PM
Cloudy Weather
64°
Feels Like 66°
31
Humidity: 54%
UV Index: 4
Wind: 12 mph
3 PM
Partly Sunny with Showers
64°
Feels Like 63°
31
Humidity: 56%
UV Index: 3
Wind: 13 mph
4 PM
Cloudy Weather
63°
Feels Like 61°
31
Humidity: 57%
UV Index: 2
Wind: 13 mph
5 PM
Partly Sunny with Showers
63°
Feels Like 57°
31
Humidity: 59%
UV Index: 1
Wind: 13 mph
6 PM
Cloudy Weather
61°
Feels Like 57°
31
Humidity: 62%
UV Index: 1
Wind: 12 mph
7 PM
Cloudy Weather
59°
Feels Like 55°
31
Humidity: 66%
UV Index: 1
Wind: 10 mph
8 PM
Cloudy Night
57°
Feels Like 54°
25
Humidity: 69%
UV Index: 0
Wind: 10 mph
9 PM
Cloudy Night
55°
Feels Like 52°
25
Humidity: 73%
UV Index: 0
Wind: 9 mph
10 PM
Rainy Night
55°
Feels Like 52°
25
Humidity: 74%
UV Index: 0
Wind: 8 mph
11 PM
Cloudy Night
55°
Feels Like 52°
25
Humidity: 77%
UV Index: 0
Wind: 8 mph

Hourly Air Quality Forecast - AQI (US EPA)

9 AM
83 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3.25 µg/m³
  • PM10: 7.68 µg/m³
  • O3: 0.065 ppm
  • NO2: 0.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

10 AM
82 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3.24 µg/m³
  • PM10: 8.14 µg/m³
  • O3: 0.064 ppm
  • NO2: 0.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

11 AM
82 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 3.14 µg/m³
  • PM10: 8.17 µg/m³
  • O3: 0.064 ppm
  • NO2: 0.2 ppb
  • SO2: 0.3 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

12 PM
81 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.97 µg/m³
  • PM10: 7.87 µg/m³
  • O3: 0.064 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

1 PM
82 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.8 µg/m³
  • PM10: 7.43 µg/m³
  • O3: 0.064 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

2 PM
82 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.68 µg/m³
  • PM10: 7.08 µg/m³
  • O3: 0.064 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

3 PM
82 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.59 µg/m³
  • PM10: 6.81 µg/m³
  • O3: 0.064 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

4 PM
81 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.53 µg/m³
  • PM10: 6.66 µg/m³
  • O3: 0.064 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

5 PM
81 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.48 µg/m³
  • PM10: 6.54 µg/m³
  • O3: 0.064 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

6 PM
80 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.44 µg/m³
  • PM10: 6.43 µg/m³
  • O3: 0.063 ppm
  • NO2: 0.1 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

7 PM
78 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.36 µg/m³
  • PM10: 6.26 µg/m³
  • O3: 0.063 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

8 PM
76 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.26 µg/m³
  • PM10: 6.05 µg/m³
  • O3: 0.062 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

9 PM
74 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.16 µg/m³
  • PM10: 5.89 µg/m³
  • O3: 0.062 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

10 PM
73 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.1 µg/m³
  • PM10: 5.88 µg/m³
  • O3: 0.061 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.

11 PM
71 AQI
Moderate air quality Dominant pollutant: O3
Details

Pollutant Concentrations:

  • PM2.5: 2.09 µg/m³
  • PM10: 6.03 µg/m³
  • O3: 0.061 ppm
  • NO2: 0.2 ppb
  • SO2: 0.2 ppb
  • CO: 0.12 ppm

Health Recommendations:

Air quality is acceptable; some pollutants may pose a risk for a small number of unusually sensitive people.