Today | Weather | Saturday, May 30, 2026

Weather in San Mateo, California

11:56 PM
Today
Cloudy Night
Day 72°
Night 50°
Precipitation 2 %
Wind 8 mph

San Mateo Weather Forecast Updated

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

Day

84°

Night

55°

Wind

7 mph

UV Index

11

Precipitation

0 %

Air Quality in San Mateo

NOW
39 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 3.8 µg/m³
PM10 18.45 µg/m³
O3 0.043 ppm
NO2 0.3 ppb
SO2 0.3 ppb
CO 0.10 ppm
NH3 0 µg/m³
NO 0 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)
PM2.53.8 µg/m³
PM1018.45 µg/m³
O383.73 µg/m³
NO20.53 µg/m³
SO20.72 µg/m³
CO115.09 µg/m³
NH30 µg/m³
NO0 µg/m³