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Today | Weather | Thursday, August 21, 2025
Heat Advisory (Issued when high temperatures and humidity create conditions that may be hazardous during outdoor activity or prolonged exposure.)

Weather in Fontana, California

05:19 PM
Now
Cloudy WeatherCloudy weather, overcast skies with clouds.
100° F
Feels Like 100°
Precipitation 0 %
Wind 13 mph
UV Index (0 - 11+) 11
Humidity 20 %
Today
Cloudy WeatherCloudy weather, overcast skies with clouds.
Day 106°
Night 72°
Precipitation 0 %
Wind 7 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.

Other:

Sunny to partly overcast and hot; heat will be dangerous, minimize outdoor activity.

Fontana Weather Forecast Updated

40 minutes ago
Last updated on

Weather Forecast History

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

Sunny WeatherSunny weather, clear skies and sunny weather.

Day

99°

Night

66°

Wind

8 mph

UV Index

10

Precipitation

0

Air quality in Fontana

NOW
90 AQI
Moderate air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 10.08 µg/m³
PM10 46.83 µg/m³
O₃ 94.52 ppb
NO₂ 11.60 ppb
SO₂ 1.52 ppb
CO 252.52 ppb
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide

Health Recommendations:

Air quality is currently in the acceptable range. However, sensitive individuals should be aware of potential risks from certain pollutants.

View Hourly Air Quality Forecast