Today | Weather | Monday, January 5, 2026

Weather in San Marcos, California

06:08 AM
Now
Cloudy Night
55° F
Feels Like 54°
Precipitation 34 %
Wind 5 mph
Humidity 89 %
Today
Rainy Weather
Day 64°
Night 48°
Precipitation 55 %
Wind 6 mph
UV Index (0 - 11+) 1

San Marcos Weather Forecast Updated

Last updated on

Air Quality in San Marcos

NOW
47 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 0.61 µg/m³
PM10 1.32 µg/m³
O3 0.051 ppm
NO2 0.2 ppb
SO2 0.1 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)
PM2.50.61 µg/m³
PM101.32 µg/m³
O399.15 µg/m³
NO20.33 µg/m³
SO20.17 µg/m³
CO114.35 µg/m³
NH30 µg/m³
NO0 µg/m³