Today | Weather | Thursday, December 4, 2025

Active Weather Warnings

Wind Advisory

Weather in Simi Valley, California

01:29 AM

Now

54° F

Feels Like 46°

Precipitation 0 %

Wind 15 mph

Humidity 37 %

Today

Day 70°

Night 43°

Precipitation 0 %

Wind 8 mph

UV Index (0 - 11+) 3

Simi Valley Weather Forecast Updated

32 minutes ago

Last updated on December 04, 2025 at 12:56 AM

Weather Forecast History

Last Year's Weather on This Day (December 4, 2024)

Day

66°

Night

45°

Wind

6 mph

Precipitation

0 %

Air Quality in Simi Valley

NOW

65 AQI

Moderate air quality Dominant pollutant: PM_2.5

Pollutant Concentrations:

PM_2.5 19.12 µg/m³

PM₁₀ 28.18 µg/m³

O₃ 0.050 ppm

NO₂ 1.1 ppb

SO₂ 0.4 ppb

CO 0.18 ppm

NH₃ 0.27 µg/m³

NO 0 µg/m³

PM_2.5 – 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 acceptable; however, for some pollutants, there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.

Show raw pollutant concentrations (µg/m³)

PM_2.5 – 19.12 µg/m³

PM₁₀ – 28.18 µg/m³

O₃ – 98.8 µg/m³

NO₂ – 2.03 µg/m³

SO₂ – 0.98 µg/m³

CO – 202.24 µg/m³

NH₃ – 0.27 µg/m³

NO – 0 µg/m³

View Hourly Air Quality Forecast

Weather Alerts and Warnings for Simi Valley

Moderate Expected Likely

Wind Advisory

Wind Advisory issued December 3 at 1:09PM PST until December 4 at 3:00PM PST by NWS Los Angeles/Oxnard CA

Dec 3, 1:09 PM → Dec 4, 3:00 PM

WHAT: Northeast gusts 25 to 35 mph, with local areas gusting up
to 45 mph in favored foothills.

WHERE: Calabasas and Agoura Hills, Central Ventura County
Valleys, Malibu Coast, Santa Clarita Valley, Southeastern Ventura
County Valleys, Ventura County Beaches, and Ventura County Inland
Coast.

WHEN: Until 3 PM PST Thursday.

IMPACTS: Gusty winds will blow around unsecured objects. Tree
limbs could be blown down and a few power outages may result.
Entire trees may also be blown over more easily due to wet soils
from from the November rains.

ADDITIONAL DETAILS: There is a chance winds remain under advisory
criteria today. Relative lulls are possible in the late afternoon
through evening hours today. Higher confidence in stronger and
more widespread winds late tonight into Thursday afternoon.

+ Read More

Winds this strong can make driving difficult, especially for high profile vehicles. Be cautious parking under trees. Secure outdoor objects.

Updated: Dec 4, 12:56 AM Source: NWS Alert