Air Quality in San Marcos, United States
Clear
35.8°C · 30.9% humidity
35.8°
Feels 35.8°
16
Good
Air quality is satisfactory. Enjoy outdoor activities.
1 station
Nearby Monitoring Stations
San Marcos's air quality — share it
AQI Forecast
Calibrated
51
7pm
51
51
16
10pm
24
31
36
1am
40
42
44
4am
45
46
47
7am
48
48
48
10am
49
49
49
1pm
49
49
49
4pm
49
49
Station readings
49h ago
AQI 49
PM2.5 11.8 µg/m³ · 49h ago
Air Quality Index Trend
46h · 6 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.
30.9%
Humidity
35.7 km/h
Wind SSW
1012.6 hPa
Pressure
9.4
UV Very High
GoodModerateUSGUnhealthyVery UnhealthyHazardous
Which pollutant is driving the AQI?
PM2.5▲
3.8 µg/m³
PM10
13.7 µg/m³
050100150200300500
What is the weather forecast for San Marcos?
Temperature & Precipitation
PM2.5 Trend
46h · 6 stationsPM2.53.8 µg/m³
✓ WHO
Good
PM1013.7 µg/m³
Good
UV INDEX9.4
Very High
Station readings (1 station within 25 km)
3.8
Median
3.8
Average
3.8
Low
3.8
High
PM2.5 µg/m³ · Model: 6.25 · Bias: +2.5
What is the 7-day forecast for San Marcos?
08-03
38.9° 23.4°
08-04
27.8° 24.8°
5.75 mm
08-05
36.2° 24.7°
08-06
36.7° 24.8°
08-07
38.8° 23.8°
08-08
32.7° 22.0°
0.19 mm
08-09
35.1° 24.3°
0.56 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 2026-08-08T03:56 UTC.