San Jose, California, United States Historical Air Quality Analysis
Dive into detailed Air Quality Insights with historical data, monthly patterns, and yearly trends at your fingertips!
September Air Quality Analysis
San Jose, California, United States
AQI Trends: Highest and Lowest
Same Day Analysis (29th September ):
On this day, AQI across the 5 years varied significantly: 2025 ranks 4th highest AQI at 26 of Good air quality, showing improvement over 2024, 2022 and 2021 on the same day.
Download 2024 Annual Data
World Air Quality Report

Day & Night AQI Trend: 29th Sep - 30th Sep 2025
San Jose, California, United States
6 AM29th Sep 2025
7 PM
5 AM30th Sep 2025
36AQI
19AQI
55AQI
22AQI
In the last 24 hours,
San Jose's AQI reached its highest point of 55 at 10 PM during the Night, while the lowest point, 19, was recorded at 9 AM during the Day between 29th Sep and 30th Sep 2025.
Day & Night AQI Trend : Aug - Sep 2025
San Jose, California, United States
24°C18/33°C
24°C18/34°C
24°C19/34°C
23°C16/34°C
21°C16/29°C
18°C15/22°C
20°C15/28°C
20°C16/27°C
20°C16/26°C
20°C17/25°C
20°C17/24°C
19°C16/24°C
20°C15/28°C
19°C15/27°C
19°C15/26°C
23°C15/33°C
24°C19/33°C
24°C18/34°C
23°C19/29°C
24°C19/31°C
22°C16/31°C
20°C12/29°C
22°C15/33°C
25°C17/37°C
23°C19/31°C
22°C17/30°C
22°C16/32°C
20°C15/27°C
20°C16/23°C
21°C18/25°C
--°C/°C
43AQI
38AQI
41AQI
37AQI
2025 Days Vs Air Quality
San Jose, California, United States
89%
242
11%
30
Total number of days with different AQI categories in last 273 days in 2025 (92 days remaining)
Under WHO’s Safe Air Quality Limits: 89%
Health Risk Level:
Low
In 2025, 89% of 273 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 Jose, California, United States
AQI levels in 2025
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
75AQI
60AQI
52AQI
43AQI
51AQI
50AQI
31AQI
34AQI
47AQI
48AQI
38AQI
30AQI
42AQI
43AQI
54AQI
61AQI
59AQI
58AQI
64AQI
49AQI
49AQI
56AQI
60AQI
68AQI
56AQI
43AQI
43AQI
48AQI
48AQI
49AQI
47AQI
51AQI
33AQI
27AQI
23AQI
26AQI
30AQI
25AQI
27AQI
30AQI
33AQI
31AQI
26AQI
24AQI
27AQI
37AQI
40AQI
27AQI
34AQI
34AQI
31AQI
37AQI
47AQI
39AQI
38AQI
37AQI
42AQI
47AQI
53AQI
42AQI
27AQI
27AQI
27AQI
31AQI
25AQI
35AQI
33AQI
39AQI
36AQI
30AQI
27AQI
25AQI
27AQI
55AQI
48AQI
24AQI
27AQI
27AQI
24AQI
31AQI
32AQI
32AQI
32AQI
44AQI
35AQI
26AQI
30AQI
27AQI
21AQI
24AQI
25AQI
29AQI
28AQI
28AQI
25AQI
29AQI
21AQI
23AQI
32AQI
33AQI
25AQI
40AQI
47AQI
44AQI
37AQI
41AQI
35AQI
37AQI
40AQI
48AQI
45AQI
45AQI
51AQI
43AQI
31AQI
27AQI
29AQI
41AQI
42AQI
45AQI
41AQI
39AQI
31AQI
37AQI
40AQI
45AQI
49AQI
45AQI
39AQI
40AQI
32AQI
25AQI
23AQI
28AQI
33AQI
37AQI
36AQI
36AQI
44AQI
34AQI
47AQI
42AQI
31AQI
37AQI
26AQI
21AQI
33AQI
37AQI
25AQI
40AQI
51AQI
54AQI
53AQI
43AQI
55AQI
49AQI
40AQI
40AQI
33AQI
26AQI
31AQI
50AQI
51AQI
53AQI
50AQI
52AQI
50AQI
44AQI
45AQI
52AQI
48AQI
43AQI
42AQI
44AQI
34AQI
29AQI
32AQI
41AQI
44AQI
41AQI
33AQI
35AQI
31AQI
44AQI
40AQI
45AQI
39AQI
33AQI
27AQI
24AQI
35AQI
43AQI
44AQI
43AQI
34AQI
24AQI
24AQI
25AQI
24AQI
28AQI
27AQI
29AQI
19AQI
21AQI
21AQI
19AQI
21AQI
19AQI
26AQI
33AQI
34AQI
33AQI
33AQI
35AQI
34AQI
41AQI
34AQI
43AQI
35AQI
33AQI
48AQI
44AQI
37AQI
41AQI
34AQI
25AQI
41AQI
21AQI
20AQI
24AQI
31AQI
37AQI
48AQI
57AQI
50AQI
41AQI
42AQI
45AQI
52AQI
48AQI
37AQI
39AQI
45AQI
40AQI
50AQI
41AQI
37AQI
32AQI
35AQI
29AQI
26AQI
23AQI
21AQI
34AQI
41AQI
41AQI
26AQI
29AQI
41AQI
42AQI
43AQI
48AQI
48AQI
39AQI
40AQI
49AQI
52AQI
47AQI
51AQI
52AQI
24AQI
26AQI
50AQI
34AQI
31AQI
36AQI
36AQI
43AQI
30AQI
39AQI
38AQI
No. of days
202538AQI
Highest AQI recorded in
January50AQI
Lowest AQI recorded in
July30AQI
202436AQI
Highest AQI recorded in
December54AQI
Lowest AQI recorded in
March23AQI
202333AQI
Highest AQI recorded in
December50AQI
Lowest AQI recorded in
March24AQI
202239AQI
Highest AQI recorded in
January51AQI
Lowest AQI recorded in
July27AQI
202140AQI
Highest AQI recorded in
September49AQI
Lowest AQI recorded in
June32AQI
202045AQI
Highest AQI recorded in
September73AQI
Lowest AQI recorded in
May28AQI
Most & Least Polluted Years Over the Last 6 Years
San Jose's annual 2025 AQI (38) shows an average percentage change of -1.4% (improved AQI) compared to previous years: 2020 (45), 2021 (40), 2022 (39), 2023 (33), 2024 (36).