Today | Weather | Thursday, February 26, 2026

Weather in Costa Mesa, California

12:38 AM
Now
Cloudy Night
57° F
Feels Like 57°
Precipitation 0 %
Wind 4 mph
Humidity 93 %
Today
Cloudy Weather
Day 73°
Night 54°
Precipitation 0 %
Wind 6 mph
UV Index (0 - 11+) 5

Costa Mesa Weather Forecast Updated

43 minutes ago
Last updated on
Weather Forecast History
Last Year's Weather on This Day (February 26, 2025)
Cloudy Weather

Day

70°

Night

46°

Wind

4 mph

UV Index

5

Precipitation

40 %

Air Quality in Costa Mesa

NOW
33 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 4.87 µg/m³
PM10 11.49 µg/m³
O3 0.035 ppm
NO2 0.7 ppb
SO2 0.2 ppb
CO 0.11 ppm
NH3 0.02 µg/m³
NO 0 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

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

Show raw pollutant concentrations (µg/m³)
PM2.54.87 µg/m³
PM1011.49 µg/m³
O368.99 µg/m³
NO21.33 µg/m³
SO20.4 µg/m³
CO126.04 µg/m³
NH30.02 µg/m³
NO0 µg/m³