Today | Weather | Thursday, May 21, 2026
Active Weather Warnings

Weather in San Bernardino, California

08:20 AM
Now
Cloudy Weather
59° F
Feels Like 64°
Precipitation 0 %
Wind 1 mph
UV Index (0 - 11+) 2
Humidity 49 %
Today
Cloudy Weather
Day 90°
Night 57°
Precipitation 0 %
Wind 8 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.

San Bernardino Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (May 21, 2025)
Sunny Weather

Day

97°

Night

59°

Wind

4 mph

UV Index

11

Precipitation

0 %

Air Quality in San Bernardino

NOW
39 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 8.68 µg/m³
PM10 20.93 µg/m³
O3 0.042 ppm
NO2 1 ppb
SO2 0.5 ppb
CO 0.12 ppm
NH3 0.26 µg/m³
NO 0.15 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)
PM2.58.68 µg/m³
PM1020.93 µg/m³
O381.69 µg/m³
NO21.95 µg/m³
SO21.18 µg/m³
CO133.37 µg/m³
NH30.26 µg/m³
NO0.15 µg/m³

Weather Alerts and Warnings for San Bernardino

Air Quality Alert

Air Quality Alert issued May 20 at 5:44PM PDT by NWS San Diego CA
May 20, 5:44 PM May 21, 5:45 PM
WHAT: The South Coast AQMD has issued an air quality alert due to
increased fine particle pollution from wildfire smoke. Visit
https://www.aqmd.gov/alertinfo to check current and forecasted air
quality levels.

WHERE: in portions of Riverside, San Bernardino, and Los Angeles
Counties. Levels of particle pollution can vary by time and
location depending on fire activity and local weather conditions.

WHEN: until Thursday at 10:00 PM.

IMPACTS: Particles in wildfire smoke can get deep into the lungs
and cause serious health problems such as heart attacks, strokes,
asthma attacks, and difficulty breathing. Everyone can be affected,
but people with lung or heart disease, older adults, people who are
pregnant, children, and those who spend a lot of time outdoors are
at greater risk.
+ Read More
To protect your health, if you smell or see smoke: * Remain indoors with windows and doors closed * Avoid intense outdoor physical activity * Run your air conditioner and/or an air purifier * If you must be outdoors, keep the time brief and wear a well- fitting N-95 mask * Do not use whole house fans or swamp coolers that bring in outside air if you have other methods to stay cool * Avoid other sources of pollution such as fireplaces, candles, incense, grilling, and gasoline-powered lawn and garden equipment
Updated: May 21, 6:56 AM Source: NWS Alert