Today | Weather | Tuesday, August 4, 2026

Active Weather Warnings

Heat Advisory

Weather in Sunnyvale, California

03:20 PM

Now

79° F

Feels Like 84°

Precipitation 0 %

Wind 9 mph

UV Index (0 - 11+) 7

Humidity 54 %

Today

Day 82°

Night 61°

Precipitation 0 %

Wind 7 mph

UV Index (0 - 11+) 10

Warning: High UV Index Today: 10

High risk of harm from unprotected sun exposure. Take precautions: wear a hat, sunglasses, and apply sunscreen regularly if you’ll be outdoors for extended periods.

Sunnyvale Weather Forecast Updated

1 minute ago

Last updated on August 04, 2026 at 3:18 PM

Weather Forecast History

Last Year's Weather on This Day (August 4, 2025)

Day

84°

Night

55°

Wind

6 mph

Precipitation

0 %

Air Quality in Sunnyvale

NOW

42 AQI

Good air quality Dominant pollutant: PM_2.5

Pollutant Concentrations:

PM_2.5 10.15 µg/m³

PM₁₀ 29.28 µg/m³

O₃ 0.040 ppm

NO₂ 0.2 ppb

SO₂ 0.4 ppb

CO 0.07 ppm

NH₃ 0 µg/m³

NO 0.08 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 considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)

PM_2.5 – 10.15 µg/m³

PM₁₀ – 29.28 µg/m³

O₃ – 79.31 µg/m³

NO₂ – 0.38 µg/m³

SO₂ – 0.95 µg/m³

CO – 77.25 µg/m³

NH₃ – 0 µg/m³

NO – 0.08 µg/m³

View Hourly Air Quality Forecast

Weather Alerts and Warnings for Sunnyvale

Moderate Expected Likely

Heat Advisory

Heat Advisory issued August 4 at 9:14AM PDT until August 4 at 10:00PM PDT by NWS San Francisco CA

Aug 4, 10:00 AM → Aug 4, 10:00 PM

WHAT: Temperatures in the 90s to low 100s.

WHERE: The Santa Clara Valley and Eastern Hills.

WHEN: Until 10 PM PDT this evening.

IMPACTS: This level of heat affects most individuals sensitive to
heat, especially those without effective cooling and/or adequate
hydration. Impacts possible in some health systems and in
heat-sensitive industries.

ADDITIONAL DETAILS: Hottest temperatures southern interior Santa
Clara Valley and interior Eastern Hills.

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Hydration is a critical piece to surviving the heat. Drink water, and if possible, take water to those who are vulnerable. Beat the heat and check the backseat! Do not leave young children or pets in unattended vehicles.Car interiors will reach lethal temperatures in a matter of minutes. Stay cool, stay hydrated, stay informed.

Updated: Aug 4, 3:18 PM Source: NWS Alert