San Marcos, Texas, United States Historical Air Quality Analysis
Dive into detailed Air Quality Insights with historical data, monthly patterns, and yearly trends at your fingertips!
October Air Quality Analysis
San Marcos, Texas, United States
AQI Trends: Highest and Lowest
Same Day Analysis (4th October ):
On this day, AQI across the 1 years varied significantly: 2025 ranks 1st highest AQI at 58 of Moderate air quality on the same day.
Download 2024 Annual Data
World Air Quality Report

Day & Night AQI Trend: 4th Oct - 5th Oct 2025
San Marcos, Texas, United States
7 AM4th Oct 2025
7 PM
6 AM5th Oct 2025
66AQI
53AQI
59AQI
47AQI
In the last 24 hours,
San Marcos's AQI reached its highest point of 66 at 3 PM during the Day, while the lowest point, 47, was recorded at 6 AM during the Night between 4th Oct and 5th Oct 2025.
Day & Night AQI Trend : Sep - Oct 2025
San Marcos, Texas, United States
32°C25/40°C
27°C24/33°C
24°C22/27°C
27°C22/34°C
26°C17/35°C
27°C19/37°C
28°C20/37°C
29°C22/38°C
28°C21/37°C
29°C21/38°C
29°C22/38°C
29°C21/37°C
28°C21/37°C
29°C22/37°C
29°C23/37°C
28°C22/37°C
29°C24/38°C
30°C25/38°C
31°C26/38°C
29°C26/35°C
28°C22/34°C
27°C18/36°C
26°C17/36°C
26°C17/35°C
26°C17/35°C
28°C18/37°C
27°C18/37°C
28°C18/37°C
28°C20/36°C
27°C19/35°C
--°C/°C
46AQI
39AQI
42AQI
39AQI
2025 Days Vs Air Quality
San Marcos, Texas, United States
76%
147
24%
46
Total number of days with different AQI categories in last 278 days in 2025 (87 days remaining)
Under WHO’s Safe Air Quality Limits: 76%
Health Risk Level:
Low
In 2025, 76% of 278 days were within WHO’s safe air quality limits. The risk of health issues is Low, but the long-term effects, especially on vulnerable individuals, remain uncertain.
Annual Air Quality Insights
San Marcos, Texas, United States
AQI levels in 2025
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
30AQI
26AQI
26AQI
42AQI
68AQI
59AQI
54AQI
64AQI
71AQI
61AQI
30AQI
20AQI
22AQI
31AQI
36AQI
40AQI
42AQI
50AQI
40AQI
42AQI
46AQI
46AQI
40AQI
54AQI
62AQI
38AQI
26AQI
43AQI
41AQI
55AQI
50AQI
58AQI
48AQI
51AQI
45AQI
53AQI
57AQI
43AQI
28AQI
28AQI
33AQI
47AQI
40AQI
42AQI
26AQI
33AQI
37AQI
33AQI
39AQI
47AQI
61AQI
66AQI
69AQI
56AQI
62AQI
67AQI
54AQI
58AQI
48AQI
54AQI
58AQI
58AQI
34AQI
33AQI
34AQI
36AQI
43AQI
47AQI
50AQI
58AQI
54AQI
50AQI
54AQI
60AQI
57AQI
48AQI
43AQI
32AQI
26AQI
42AQI
54AQI
49AQI
32AQI
37AQI
56AQI
53AQI
50AQI
32AQI
37AQI
44AQI
29AQI
23AQI
26AQI
22AQI
22AQI
23AQI
45AQI
46AQI
53AQI
40AQI
47AQI
61AQI
60AQI
54AQI
45AQI
33AQI
42AQI
47AQI
38AQI
30AQI
33AQI
49AQI
60AQI
62AQI
47AQI
44AQI
42AQI
48AQI
39AQI
34AQI
27AQI
27AQI
30AQI
36AQI
44AQI
58AQI
54AQI
48AQI
32AQI
31AQI
34AQI
30AQI
33AQI
35AQI
35AQI
36AQI
37AQI
28AQI
27AQI
30AQI
32AQI
49AQI
31AQI
36AQI
54AQI
29AQI
31AQI
34AQI
37AQI
40AQI
39AQI
45AQI
47AQI
41AQI
44AQI
47AQI
44AQI
41AQI
30AQI
32AQI
31AQI
36AQI
36AQI
33AQI
31AQI
49AQI
46AQI
44AQI
40AQI
38AQI
36AQI
46AQI
46AQI
52AQI
43AQI
49AQI
46AQI
44AQI
32AQI
24AQI
18AQI
19AQI
21AQI
32AQI
40AQI
41AQI
42AQI
38AQI
37AQI
58AQI
64AQI
67AQI
58AQI
42AQI
45AQI
46AQI
42AQI
44AQI
37AQI
37AQI
62AQI
No. of days
202542AQI
Highest AQI recorded in
October62AQI
Lowest AQI recorded in
August37AQI
Most & Least Polluted Years Over the Last 1 Years
San Marcos's annual 2025 AQI (42) shows an average percentage change of NaN% (improved AQI) compared to previous years: .