Today | Weather | Tuesday, June 30, 2026

Weather in San Mateo, California

12:19 PM
Now
Cloudy Weather
70° F
Feels Like 75°
Precipitation 0 %
Wind 10 mph
UV Index (0 - 11+) 10
Humidity 62 %
Today
Cloudy Weather
Day 72°
Night 54°
Precipitation 1 %
Wind 10 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 Mateo Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (June 30, 2025)
Cloudy Weather

Day

75°

Night

55°

Wind

9 mph

UV Index

11

Precipitation

1 %

Air Quality in San Mateo

NOW
36 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 6.24 µg/m³
PM10 21.7 µg/m³
O3 0.039 ppm
NO2 0.2 ppb
SO2 0.4 ppb
CO 0.07 ppm
NH3 0 µg/m³
NO 0.09 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)
PM2.56.24 µg/m³
PM1021.7 µg/m³
O375.69 µg/m³
NO20.36 µg/m³
SO21.15 µg/m³
CO83.68 µg/m³
NH30 µg/m³
NO0.09 µg/m³