Today | Weather | Friday, October 30, 2026

Weather in San Marcos, California

03:24 AM
Now
Cloudy Weather
64° F
Feels Like 64°
Precipitation 49 %
Wind 4 mph
Humidity 84 %
Today
Rainy Weather
Day 72°
Night 55°
Precipitation 56 %
Wind 6 mph
UV Index (0 - 11+) 1

San Marcos Weather Forecast Updated

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

Day

88°

Night

48°

Wind

4 mph

Precipitation

0 %

Air Quality in San Marcos

NOW
50 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 1.79 µg/m³
PM10 6.3 µg/m³
O3 0.054 ppm
NO2 0.1 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)
PM2.5 – 1.79 µg/m³
PM10 – 6.3 µg/m³
O3 – 105.61 µg/m³
NO2 – 0.2 µg/m³
SO2 – 0.21 µg/m³
CO – 117.68 µg/m³
NH3 – 0 µg/m³
NO – 0 µg/m³