Hourly Weather Forecast for Fontana, California

Hourly Weather | Today › Thursday, May 21, 2026

Active Weather Warnings

Air Quality Alert

Fontana, California

9 AM

73°

Feels Like 77°

Humidity: 32%

UV Index: 3

Wind: 4 mph

10 AM

77°

Feels Like 82°

Humidity: 29%

UV Index: 5

Wind: 6 mph

11 AM

81°

Feels Like 88°

Humidity: 25%

UV Index: 8

Wind: 7 mph

12 PM

84°

Feels Like 91°

Humidity: 22%

UV Index: 10

Wind: 8 mph

1 PM

86°

Feels Like 91°

Humidity: 21%

UV Index: 11

Wind: 10 mph

2 PM

88°

Feels Like 91°

Humidity: 20%

UV Index: 10

Wind: 13 mph

3 PM

90°

Feels Like 91°

Humidity: 20%

UV Index: 8

Wind: 14 mph

4 PM

88°

Feels Like 88°

Humidity: 21%

UV Index: 5

Wind: 14 mph

5 PM

86°

Feels Like 84°

Humidity: 22%

UV Index: 3

Wind: 14 mph

6 PM

84°

Feels Like 82°

Humidity: 24%

UV Index: 2

Wind: 13 mph

7 PM

81°

Feels Like 79°

Humidity: 28%

UV Index: 1

Wind: 10 mph

8 PM

77°

Feels Like 73°

Humidity: 33%

UV Index: 0

Wind: 9 mph

9 PM

73°

Feels Like 72°

Humidity: 38%

UV Index: 0

Wind: 8 mph

10 PM

72°

Feels Like 68°

Humidity: 44%

UV Index: 0

Wind: 7 mph

11 PM

68°

Feels Like 66°

Humidity: 50%

UV Index: 0

Wind: 6 mph

Hourly Air Quality Forecast - AQI (US EPA)

9 AM

37 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 6.94 µg/m³
PM₁₀: 17.38 µg/m³
O₃: 0.040 ppm
NO₂: 0.4 ppb
SO₂: 0.3 ppb
CO: 0.09 ppm

Health Recommendations:

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

10 AM

37 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 6.99 µg/m³
PM₁₀: 17.76 µg/m³
O₃: 0.040 ppm
NO₂: 0.3 ppb
SO₂: 0.3 ppb
CO: 0.09 ppm

Health Recommendations:

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

11 AM

38 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 7.18 µg/m³
PM₁₀: 18.67 µg/m³
O₃: 0.041 ppm
NO₂: 0.3 ppb
SO₂: 0.3 ppb
CO: 0.09 ppm

Health Recommendations:

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

12 PM

39 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 7.51 µg/m³
PM₁₀: 20.03 µg/m³
O₃: 0.042 ppm
NO₂: 0.2 ppb
SO₂: 0.3 ppb
CO: 0.09 ppm

Health Recommendations:

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

1 PM

40 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 7.93 µg/m³
PM₁₀: 21.53 µg/m³
O₃: 0.043 ppm
NO₂: 0.2 ppb
SO₂: 0.3 ppb
CO: 0.09 ppm

Health Recommendations:

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

2 PM

42 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 8.24 µg/m³
PM₁₀: 22.52 µg/m³
O₃: 0.045 ppm
NO₂: 0.2 ppb
SO₂: 0.3 ppb
CO: 0.10 ppm

Health Recommendations:

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

3 PM

43 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 8.34 µg/m³
PM₁₀: 22.65 µg/m³
O₃: 0.047 ppm
NO₂: 0.1 ppb
SO₂: 0.3 ppb
CO: 0.10 ppm

Health Recommendations:

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

4 PM

44 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 8.38 µg/m³
PM₁₀: 22.7 µg/m³
O₃: 0.048 ppm
NO₂: 0.2 ppb
SO₂: 0.3 ppb
CO: 0.10 ppm

Health Recommendations:

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

5 PM

45 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 8.46 µg/m³
PM₁₀: 22.99 µg/m³
O₃: 0.049 ppm
NO₂: 0.2 ppb
SO₂: 0.3 ppb
CO: 0.10 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:

PM_2.5: 8.61 µg/m³
PM₁₀: 23.47 µg/m³
O₃: 0.049 ppm
NO₂: 0.3 ppb
SO₂: 0.4 ppb
CO: 0.10 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:

PM_2.5: 8.72 µg/m³
PM₁₀: 23.51 µg/m³
O₃: 0.050 ppm
NO₂: 0.4 ppb
SO₂: 0.4 ppb
CO: 0.10 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:

PM_2.5: 9.15 µg/m³
PM₁₀: 23.48 µg/m³
O₃: 0.051 ppm
NO₂: 0.4 ppb
SO₂: 0.4 ppb
CO: 0.11 ppm

Health Recommendations:

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

9 PM

48 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 10.15 µg/m³
PM₁₀: 23.92 µg/m³
O₃: 0.052 ppm
NO₂: 0.4 ppb
SO₂: 0.4 ppb
CO: 0.12 ppm

Health Recommendations:

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

10 PM

49 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 10.89 µg/m³
PM₁₀: 24.35 µg/m³
O₃: 0.053 ppm
NO₂: 0.3 ppb
SO₂: 0.3 ppb
CO: 0.12 ppm

Health Recommendations:

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

11 PM

49 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 11.17 µg/m³
PM₁₀: 24.5 µg/m³
O₃: 0.053 ppm
NO₂: 0.3 ppb
SO₂: 0.3 ppb
CO: 0.13 ppm

Health Recommendations:

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

Current Real-Time Air Quality Report

Weather Alerts and Warnings for Fontana

Air Quality Alert

Air Quality Alert issued May 20 at 5:44PM PDT by NWS San Diego CA

May 20, 5:44 PM → May 21, 5:45 PM

WHAT: The South Coast AQMD has issued an air quality alert due to
increased fine particle pollution from wildfire smoke. Visit
https://www.aqmd.gov/alertinfo to check current and forecasted air
quality levels.

WHERE: in portions of Riverside, San Bernardino, and Los Angeles
Counties. Levels of particle pollution can vary by time and
location depending on fire activity and local weather conditions.

WHEN: until Thursday at 10:00 PM.

IMPACTS: Particles in wildfire smoke can get deep into the lungs
and cause serious health problems such as heart attacks, strokes,
asthma attacks, and difficulty breathing. Everyone can be affected,
but people with lung or heart disease, older adults, people who are
pregnant, children, and those who spend a lot of time outdoors are
at greater risk.

+ Read More

To protect your health, if you smell or see smoke: * Remain indoors with windows and doors closed * Avoid intense outdoor physical activity * Run your air conditioner and/or an air purifier * If you must be outdoors, keep the time brief and wear a well- fitting N-95 mask * Do not use whole house fans or swamp coolers that bring in outside air if you have other methods to stay cool * Avoid other sources of pollution such as fireplaces, candles, incense, grilling, and gasoline-powered lawn and garden equipment

Updated: May 21, 8:32 AM Source: NWS Alert

Hourly Air Quality Forecast - AQI (US EPA)

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Pollutant Concentrations:

Health Recommendations:

Weather Alerts and Warnings for Fontana

Air Quality Alert

Explore U.S. Weather Trends