Today | Weather | Tuesday, January 13, 2026

Weather in San Mateo, California

12:28 PM
Now
Cloudy Weather
55° F
Feels Like 59°
Precipitation 0 %
Wind 6 mph
UV Index (0 - 11+) 3
Humidity 69 %
Today
Sunny Weather
Day 63°
Night 43°
Precipitation 0 %
Wind 6 mph
UV Index (0 - 11+) 3

San Mateo Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (January 13, 2025)
Sunny Weather

Day

63°

Night

39°

Wind

14 mph

UV Index

3

Precipitation

0 %

Air Quality in San Mateo

NOW
87 AQI
Moderate air quality Dominant pollutant: PM2.5

Pollutant Concentrations:

PM2.5 29.39 µg/m³
PM10 37.56 µg/m³
O3 0.033 ppm
NO2 9.5 ppb
SO2 1.1 ppb
CO 0.32 ppm
NH3 0.37 µg/m³
NO 5.2 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 acceptable; however, for some pollutants, there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.

Show raw pollutant concentrations (µg/m³)
PM2.529.39 µg/m³
PM1037.56 µg/m³
O364.63 µg/m³
NO217.84 µg/m³
SO22.89 µg/m³
CO364.55 µg/m³
NH30.37 µg/m³
NO5.2 µg/m³