Hourly Weather Forecast for Costa Mesa, California

Hourly Weather | Today › Saturday, August 29, 2026

Active Weather Warnings

Heat Advisory

Costa Mesa, California

12 PM

84°

Feels Like 97°

Humidity: 62%

UV Index: 8

Wind: 8 mph

1 PM

86°

Feels Like 97°

Humidity: 59%

UV Index: 9

Wind: 8 mph

2 PM

86°

Feels Like 97°

Humidity: 57%

UV Index: 8

Wind: 9 mph

3 PM

84°

Feels Like 93°

Humidity: 59%

UV Index: 6

Wind: 9 mph

4 PM

82°

Feels Like 90°

Humidity: 63%

UV Index: 4

Wind: 9 mph

5 PM

82°

Feels Like 86°

Humidity: 67%

UV Index: 3

Wind: 9 mph

6 PM

81°

Feels Like 84°

Humidity: 68%

UV Index: 1

Wind: 9 mph

7 PM

79°

Feels Like 81°

Humidity: 71%

UV Index: 0

Wind: 8 mph

8 PM

77°

Feels Like 79°

Humidity: 76%

UV Index: 0

Wind: 7 mph

9 PM

75°

Feels Like 77°

Humidity: 82%

UV Index: 0

Wind: 6 mph

10 PM

73°

Feels Like 75°

Humidity: 83%

UV Index: 0

Wind: 6 mph

11 PM

73°

Feels Like 75°

Humidity: 83%

UV Index: 0

Wind: 6 mph

Hourly Air Quality Forecast - AQI (US EPA)

12 PM

33 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 7.08 µg/m³
PM₁₀: 24.49 µg/m³
O₃: 0.035 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

1 PM

34 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 7.64 µg/m³
PM₁₀: 25.68 µg/m³
O₃: 0.037 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

2 PM

36 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 8.21 µg/m³
PM₁₀: 27.06 µg/m³
O₃: 0.039 ppm
NO₂: 0.1 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

3 PM

37 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 8.63 µg/m³
PM₁₀: 28.24 µg/m³
O₃: 0.040 ppm
NO₂: 0.1 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

4 PM

37 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 8.73 µg/m³
PM₁₀: 29.16 µg/m³
O₃: 0.040 ppm
NO₂: 0.1 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

5 PM

37 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 8.49 µg/m³
PM₁₀: 29.33 µg/m³
O₃: 0.040 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

6 PM

37 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 7.95 µg/m³
PM₁₀: 28.78 µg/m³
O₃: 0.040 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

7 PM

37 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 7.33 µg/m³
PM₁₀: 28.05 µg/m³
O₃: 0.040 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

8 PM

37 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 6.82 µg/m³
PM₁₀: 27.59 µg/m³
O₃: 0.040 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

9 PM

38 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 6.47 µg/m³
PM₁₀: 27.26 µg/m³
O₃: 0.041 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

10 PM

38 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 6.32 µg/m³
PM₁₀: 27.22 µg/m³
O₃: 0.041 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 ppm

Health Recommendations:

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

11 PM

38 AQI

Good air quality Dominant pollutant: O₃

Details

Pollutant Concentrations:

PM_2.5: 6.37 µg/m³
PM₁₀: 27.66 µg/m³
O₃: 0.041 ppm
NO₂: 0.2 ppb
SO₂: 0.2 ppb
CO: 0.07 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 Costa Mesa

Moderate Expected Likely

Heat Advisory

Heat Advisory issued August 29 at 5:20AM PDT until August 29 at 8:00PM PDT by NWS San Diego CA

Aug 29, 5:20 AM → Aug 29, 8:00 PM

WHAT: Temperatures 82 to 88.

WHERE: Orange County Coastal Areas.

WHEN: Until 8 PM PDT this evening.

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.

Updated: Aug 29, 10:29 AM Source: NWS Alert

Hourly Air Quality Forecast - AQI (US EPA)

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Weather Alerts and Warnings for Costa Mesa

Heat Advisory

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