Today | Weather | Saturday, October 10, 2026
Active Weather Warnings

Weather in Costa Mesa, California

05:48 PM
Now
Cloudy Weather
75° F
Feels Like 75°
Precipitation 49 %
Wind 9 mph
UV Index (0 - 11+) 0
Humidity 78 %
Today
Rainy Weather
Day 77°
Night 66°
Precipitation 100 %
Wind 7 mph
UV Index (0 - 11+) 1

Costa Mesa Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (October 10, 2025)
Cloudy Night

Day

72°

Night

61°

Wind

4 mph

Precipitation

1 %

Air Quality in Costa Mesa

NOW
45 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 6.78 µg/m³
PM10 16.02 µg/m³
O3 0.049 ppm
NO2 0.5 ppb
SO2 0.2 ppb
CO 0.10 ppm
NH3 0 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)
PM2.5 – 6.78 µg/m³
PM10 – 16.02 µg/m³
O3 – 96.44 µg/m³
NO2 – 1.03 µg/m³
SO2 – 0.6 µg/m³
CO – 115.58 µg/m³
NH3 – 0 µg/m³
NO – 0 µg/m³

Weather Alerts and Warnings for Costa Mesa

Severe Expected Likely

Coastal Flood Warning

Coastal Flood Warning issued October 10 at 1:38PM PDT until October 11 at 3:00PM PDT by NWS San Diego CA
Oct 10, 1:38 PM → Oct 11, 3:00 PM
WHAT: For the Coastal Flood Warning through Sunday afternoon,
significant coastal flooding and erosion is likely. For the
Beach Hazards Statement from Sunday morning until Sunday
evening, surf of 5 to 7 feet with local sets up to 9 feet. For
the Coastal Flood Advisory from Sunday afternoon until Tuesday
afternoon, minor coastal flooding expected.

WHERE: San Diego County Coastal Areas and Orange County
Coastal Areas.

WHEN: For the Coastal Flood Warning, until 3 PM PDT Sunday.
For the Beach Hazards Statement, from Sunday morning through
Sunday evening. For the Coastal Flood Advisory, from 3 PM
Sunday to 2 PM PDT Tuesday.

IMPACTS: Numerous roads and walking paths may be closed due
to high water. Low-lying property including homes, businesses,
and some critical infrastructure may flood. Shoreline erosion
will occur during high tides in the mornings. Elevated surf
will lead to a high risk of rip currents.

ADDITIONAL DETAILS: Greatest impacts on Sunday morning from
Tropical Storm Rachel with a combination of increased swell,
onshore winds, and high tides locally over 7.5 feet. High tides
lower each day into the middle of the week.
+ Read More
Take the necessary actions to protect flood-prone property. If travel is required, do not drive around barricades or through water of unknown depth. Remain out of the water to avoid hazardous swimming conditions.
Updated: Oct 10, 4:19 PM Source: NWS Alert
Minor Expected Likely

Coastal Flood Advisory

Coastal Flood Advisory issued October 9 at 2:12AM PDT until October 13 at 2:00PM PDT by NWS San Diego CA
Oct 9, 2:12 AM → Oct 13, 2:00 PM
WHAT: For the Beach Hazards Statement, surf of 3 to 5 feet with
sets to 6 feet and dangerous rip currents expected. For the
Coastal Flood Advisory, minor coastal flooding expected during
high tides.

WHERE: San Diego County Coastal Areas and Orange County
Coastal Areas.

WHEN: For the Coastal Flood Advisory, until 2 PM PDT Tuesday.
For the Beach Hazards Statement, through Friday evening.

IMPACTS: Flooding of beach parking lots, boardwalks, and
roads with only isolated road closures expected. Minor coastal
erosion is also expected. Additionally, elevated surf will
lead to strong rip currents and dangerous swimming conditions.

ADDITIONAL DETAILS: High tides are expected to peak between
6.5 and 7.0 feet during the mornings and evenings. Additional
south swells may produce another round of elevated to high
surf Sunday through Tuesday, highest on Sunday.
+ Read More
If travel is required, allow extra time as some roads may be closed. Do not drive around barricades or through water of unknown depth. Take the necessary actions to protect flood-prone property. Remain out of the water to avoid hazardous swimming conditions.
Updated: Oct 9, 12:05 PM Source: NWS Alert