Hourly Weather Forecast for Fullerton, California

Hourly Weather | Today › Tuesday, March 17, 2026

Active Weather Warnings

Extreme Heat Watch
Heat Advisory

Fullerton, California

3 AM

61°

Feels Like 61°

Humidity: 65%

UV Index: 0

Wind: 5 mph

4 AM

59°

Feels Like 59°

Humidity: 67%

UV Index: 0

Wind: 5 mph

5 AM

57°

Feels Like 57°

Humidity: 68%

UV Index: 0

Wind: 5 mph

6 AM

55°

Feels Like 55°

Humidity: 69%

UV Index: 0

Wind: 5 mph

7 AM

59°

Feels Like 57°

Humidity: 59%

UV Index: 0

Wind: 5 mph

8 AM

63°

Feels Like 64°

Humidity: 59%

UV Index: 1

Wind: 6 mph

9 AM

66°

Feels Like 68°

Humidity: 51%

UV Index: 2

Wind: 5 mph

10 AM

73°

Feels Like 77°

Humidity: 39%

UV Index: 3

Wind: 5 mph

11 AM

79°

Feels Like 84°

Humidity: 32%

UV Index: 4

Wind: 5 mph

12 PM

82°

Feels Like 90°

Humidity: 27%

UV Index: 5

Wind: 5 mph

1 PM

88°

Feels Like 91°

Humidity: 25%

UV Index: 6

Wind: 6 mph

2 PM

90°

Feels Like 93°

Humidity: 23%

UV Index: 5

Wind: 7 mph

3 PM

90°

Feels Like 91°

Humidity: 24%

UV Index: 4

Wind: 7 mph

4 PM

90°

Feels Like 90°

Humidity: 24%

UV Index: 3

Wind: 8 mph

5 PM

86°

Feels Like 86°

Humidity: 26%

UV Index: 2

Wind: 8 mph

6 PM

84°

Feels Like 82°

Humidity: 29%

UV Index: 1

Wind: 7 mph

7 PM

79°

Feels Like 77°

Humidity: 35%

UV Index: 0

Wind: 6 mph

8 PM

75°

Feels Like 73°

Humidity: 40%

UV Index: 0

Wind: 5 mph

9 PM

73°

Feels Like 72°

Humidity: 46%

UV Index: 0

Wind: 5 mph

10 PM

70°

Feels Like 68°

Humidity: 52%

UV Index: 0

Wind: 5 mph

11 PM

66°

Feels Like 64°

Humidity: 53%

UV Index: 0

Wind: 5 mph

Hourly Air Quality Forecast - AQI (US EPA)

3 AM

55 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 14.23 µg/m³
PM₁₀: 20.53 µg/m³
O₃: 0.045 ppm
NO₂: 0.4 ppb
SO₂: 0.1 ppb
CO: 0.13 ppm

Health Recommendations:

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

4 AM

54 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 14.05 µg/m³
PM₁₀: 20.22 µg/m³
O₃: 0.044 ppm
NO₂: 0.4 ppb
SO₂: 0.1 ppb
CO: 0.13 ppm

Health Recommendations:

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

5 AM

54 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 14.05 µg/m³
PM₁₀: 20.22 µg/m³
O₃: 0.043 ppm
NO₂: 0.4 ppb
SO₂: 0.1 ppb
CO: 0.13 ppm

Health Recommendations:

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

6 AM

55 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 14.22 µg/m³
PM₁₀: 20.46 µg/m³
O₃: 0.042 ppm
NO₂: 0.4 ppb
SO₂: 0.1 ppb
CO: 0.13 ppm

Health Recommendations:

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

7 AM

55 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 14.49 µg/m³
PM₁₀: 20.88 µg/m³
O₃: 0.041 ppm
NO₂: 0.4 ppb
SO₂: 0.1 ppb
CO: 0.14 ppm

Health Recommendations:

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

8 AM

56 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 14.94 µg/m³
PM₁₀: 21.55 µg/m³
O₃: 0.040 ppm
NO₂: 0.4 ppb
SO₂: 0.1 ppb
CO: 0.14 ppm

Health Recommendations:

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

9 AM

57 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 15.5 µg/m³
PM₁₀: 22.33 µg/m³
O₃: 0.039 ppm
NO₂: 0.5 ppb
SO₂: 0.1 ppb
CO: 0.14 ppm

Health Recommendations:

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

10 AM

60 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 16.45 µg/m³
PM₁₀: 23.57 µg/m³
O₃: 0.039 ppm
NO₂: 0.6 ppb
SO₂: 0.1 ppb
CO: 0.15 ppm

Health Recommendations:

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

11 AM

63 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 18.08 µg/m³
PM₁₀: 25.64 µg/m³
O₃: 0.041 ppm
NO₂: 0.7 ppb
SO₂: 0.2 ppb
CO: 0.16 ppm

Health Recommendations:

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

12 PM

68 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 20.23 µg/m³
PM₁₀: 28.33 µg/m³
O₃: 0.045 ppm
NO₂: 0.5 ppb
SO₂: 0.2 ppb
CO: 0.16 ppm

Health Recommendations:

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

1 PM

72 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 22.38 µg/m³
PM₁₀: 31.04 µg/m³
O₃: 0.047 ppm
NO₂: 0.3 ppb
SO₂: 0.1 ppb
CO: 0.16 ppm

Health Recommendations:

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

2 PM

76 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 24.24 µg/m³
PM₁₀: 33.41 µg/m³
O₃: 0.049 ppm
NO₂: 0.2 ppb
SO₂: 0.1 ppb
CO: 0.17 ppm

Health Recommendations:

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

3 PM

80 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 26.04 µg/m³
PM₁₀: 35.67 µg/m³
O₃: 0.052 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.17 ppm

Health Recommendations:

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

4 PM

83 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 27.32 µg/m³
PM₁₀: 37.47 µg/m³
O₃: 0.054 ppm
NO₂: 0.3 ppb
SO₂: 0.2 ppb
CO: 0.17 ppm

Health Recommendations:

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

5 PM

84 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 27.8 µg/m³
PM₁₀: 38.5 µg/m³
O₃: 0.056 ppm
NO₂: 0.3 ppb
SO₂: 0.2 ppb
CO: 0.17 ppm

Health Recommendations:

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

6 PM

84 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 27.77 µg/m³
PM₁₀: 38.92 µg/m³
O₃: 0.058 ppm
NO₂: 0.4 ppb
SO₂: 0.3 ppb
CO: 0.17 ppm

Health Recommendations:

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

7 PM

82 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 26.98 µg/m³
PM₁₀: 38.4 µg/m³
O₃: 0.058 ppm
NO₂: 0.6 ppb
SO₂: 0.3 ppb
CO: 0.16 ppm

Health Recommendations:

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

8 PM

79 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 25.66 µg/m³
PM₁₀: 37.24 µg/m³
O₃: 0.057 ppm
NO₂: 0.6 ppb
SO₂: 0.3 ppb
CO: 0.16 ppm

Health Recommendations:

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

9 PM

77 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 24.44 µg/m³
PM₁₀: 35.93 µg/m³
O₃: 0.055 ppm
NO₂: 0.6 ppb
SO₂: 0.3 ppb
CO: 0.16 ppm

Health Recommendations:

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

10 PM

75 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 23.61 µg/m³
PM₁₀: 34.93 µg/m³
O₃: 0.053 ppm
NO₂: 0.6 ppb
SO₂: 0.2 ppb
CO: 0.16 ppm

Health Recommendations:

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

11 PM

74 AQI

Moderate air quality Dominant pollutant: PM_2.5

Details

Pollutant Concentrations:

PM_2.5: 23.11 µg/m³
PM₁₀: 34.27 µg/m³
O₃: 0.051 ppm
NO₂: 0.5 ppb
SO₂: 0.2 ppb
CO: 0.16 ppm

Health Recommendations:

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

Current Real-Time Air Quality Report

Weather Alerts and Warnings for Fullerton

Severe Future Likely

Extreme Heat Watch

Extreme Heat Watch issued March 14 at 5:51AM PDT until March 20 at 8:00PM PDT by NWS San Diego CA

Mar 16, 10:00 AM → Mar 20, 8:00 PM

WHAT: Dangerously hot conditions with temperatures 85 to 90 near
the coast, up to 105 inland.

WHERE: Orange County Coastal Areas, Orange County Inland Areas,
San Bernardino and Riverside County Valleys-The Inland Empire, San
Diego County Coastal Areas, San Diego County Valleys, and Santa
Ana Mountains and Foothills.

WHEN: From Monday morning through Friday evening.

IMPACTS: Heat related illnesses increase significantly during
extreme heat events.

ADDITIONAL DETAILS: High temperatures next week will be 20 to
potentially 30 degrees above
normal for this time of year, where record breaking heat is likely.

+ Read More

Updated: Mar 14, 10:45 AM Source: NWS Alert

Moderate Expected Likely

Heat Advisory

Heat Advisory issued March 17 at 12:33AM PDT until March 20 at 8:00PM PDT by NWS San Diego CA

Mar 17, 12:33 AM → Mar 20, 8:00 PM

WHAT: High temperatures in the upper 80s to mid 90s expected.

WHERE: Orange County Inland Areas.

WHEN: Until 8 PM PDT Friday.

IMPACTS: Hot temperatures may cause heat illnesses.

+ Read More

Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Do not leave young children and pets in unattended vehicles. Car interiors will reach lethal temperatures in a matter of minutes. Take extra precautions when outside. Wear lightweight and loose fitting clothing. Try to limit strenuous activities to early morning or evening. Take action when you see symptoms of heat exhaustion and heat stroke.

Updated: Mar 17, 1:06 AM Source: NWS Alert

Hourly Air Quality Forecast - AQI (US EPA)

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Weather Alerts and Warnings for Fullerton

Extreme Heat Watch

Heat Advisory

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