Air Quality in San Marcos, United States
Heavy Rain
19.7°C · 97.1% humidity
19.7°
Feels 19.7°
16
Good
Air quality is satisfactory. Enjoy outdoor activities.
1 station
Nearby Monitoring Stations
San Marcos's air quality — share it
AQI Forecast
25
6am
25
25
16
9am
19
20
22
12pm
23
23
24
3pm
24
24
25
6pm
25
25
25
9pm
25
25
25
12am
25
25
25
3am
25
25
Air Quality Index Trend
48h · 1 stnSan Marcos's air quality is primarily affected by vehicle emissions and industrial activity. Seasonal wildfire smoke and weather patterns can cause periodic air quality deterioration.
97.1%
Humidity
32.5 km/h
Wind N
1013.2 hPa
Pressure
2.9
UV Moderate
GoodModerateUSGUnhealthyVery UnhealthyHazardous
Which pollutant is driving the AQI?
PM2.5▲
3.85 µg/m³
PM10
13.7 µg/m³
050100150200300500
What is the weather forecast for San Marcos?
Temperature & Precipitation
PM2.5 Trend
48h · 1 stationPM2.53.85 µg/m³
✓ WHO
Good
PM1013.7 µg/m³
Good
UV INDEX2.9
Moderate
Station readings (1 station within 25 km)
3.85
Median
3.85
Average
3.85
Low
3.85
High
PM2.5 µg/m³ · Model: 5.9 · Bias: +2.0
What is the 7-day forecast for San Marcos?
05-29
30.3° 19.7°
60.19 mm
05-30
27.2° 21.2°
05-31
31.0° 17.9°
0.06 mm
06-01
31.7° 20.8°
06-02
31.5° 20.9°
06-03
28.8° 21.0°
0.13 mm
06-04
30.2° 21.1°
4.0 mm
Both models agree
Avg diff: 2.5°C
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Data sources: AQI from ground-level monitoring stations via AQICN. Weather forecast from ECMWF (IFS & CAMS models). AQI calculated using US EPA standard. Updated 2026-05-29T14:29 UTC.