Today | Weather | Saturday, September 20, 2025

Weather in San Francisco, California

01:32 AM

Now

61° F

Feels Like 59°

Precipitation 0 %

Wind 7 mph

Humidity 91 %

Today

Day 72°

Night 61°

Precipitation 0 %

Wind 19

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 Francisco Weather Forecast Updated

28 minutes ago

Last updated on September 20, 2025 1:04 AM

Weather Forecast History

Last Year's Weather on This Day (September 20, 2024)

Day

63°

Night

55°

Wind

9 mph

UV Index

Precipitation

Air quality in San Francisco

NOW

57 AQI

Moderate air quality Dominant pollutant: PM2.5

Pollutant Concentrations:

PM2.5 17.33 µg/m³

PM10 21.37 µg/m³

O₃ 14.53 ppb

NO₂ 12.64 ppb

SO₂ 0.89 ppb

CO 196.62 ppb

PM_2.5 – 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