Today | Weather | Thursday, February 5, 2026

Weather in San Marcos, California

05:34 PM
Now
Cloudy Night
66° F
Feels Like 64°
Precipitation 0 %
Wind 5 mph
Humidity 48 %
Today
Cloudy Weather
Day 77°
Night 52°
Precipitation 25 %
Wind 6 mph
UV Index (0 - 11+) 4

San Marcos Weather Forecast Updated

36 minutes ago
Last updated on

Air Quality in San Marcos

NOW
126 AQI
Unhealthy air quality for sensitive groups Dominant pollutant: PM2.5

Pollutant Concentrations:

PM2.5 46 µg/m³
PM10 75.89 µg/m³
O3 0.059 ppm
NO2 0.7 ppb
SO2 0.2 ppb
CO 0.22 ppm
NH3 0.02 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:

Members of sensitive groups may experience health effects. The general public is not likely to be affected.

Show raw pollutant concentrations (µg/m³)
PM2.546 µg/m³
PM1075.89 µg/m³
O3115.21 µg/m³
NO21.25 µg/m³
SO20.64 µg/m³
CO249.87 µg/m³
NH30.02 µg/m³
NO0 µg/m³