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Today | Weather | Tuesday, October 21, 2025

Weather in Simi Valley, California

07:08 PM
Now
Cloudy Night
70° F
Feels Like 68°
Precipitation 0 %
Wind 5 mph
Humidity 46 %
Today
Cloudy Weather
Day 82°
Night 55°
Precipitation 0 %
Wind 6 mph
UV Index (0 - 11+) 11

Warning: Extreme UV Index Today: 11+

Overexposure to the sun's harmful UV rays can cause sunburn and increase the risk of developing skin cancer, including melanoma. Protect yourself by wearing clothing that covers your skin, sunglasses, and a hat. Apply a broad-spectrum sunscreen with an SPF of 30 or higher every two hours, even on cloudy days. Minimize direct sun exposure during peak hours (10 AM to 4 PM) to reduce the risk.

Simi Valley Weather Forecast Updated

44 minutes ago
Last updated on

Weather Forecast History

Last Year's Weather on This Day (October 21, 2024)

Cloudy Night

Day

84°

Night

54°

Wind

4 mph

Precipitation

0

Air Quality in Simi Valley

NOW
40 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 5.81 µg/m³
PM10 16.59 µg/m³
O3 0.044 ppm
NO2 0.3 ppb
SO2 0.2 ppb
CO 0.08 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 – 5.81 µg/m³
PM10 – 16.59 µg/m³
O3 – 85.53 µg/m³
NO2 – 0.58 µg/m³
SO2 – 0.59 µg/m³
CO – 93.59 µg/m³
NH3 – 0 µg/m³
NO – 0 µg/m³
View Hourly Air Quality Forecast