Chester, California, 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
Chester, California, United States
AQI Trends: Highest and Lowest
Same Day Analysis (3rd October ):
On this day, AQI across the 1 years varied significantly: 2025 ranks 1st highest AQI at 24 of Good air quality on the same day.
Download 2024 Annual Data
World Air Quality Report

Day & Night AQI Trend: 3rd Oct - 4th Oct 2025
Chester, California, United States
6 AM3rd Oct 2025
7 PM
5 AM4th Oct 2025
48AQI
25AQI
52AQI
26AQI
In the last 24 hours,
Chester's AQI reached its highest point of 52 at 3 AM during the Night, while the lowest point, 25, was recorded at 9 AM during the Day between 3rd Oct and 4th Oct 2025.
Day & Night AQI Trend : Sep - Oct 2025
Chester, California, United States
21°C14/28°C
20°C14/27°C
18°C12/24°C
15°C9/22°C
13°C8/21°C
12°C9/17°C
12°C8/16°C
13°C8/18°C
15°C9/21°C
16°C10/23°C
15°C9/22°C
17°C10/26°C
18°C11/26°C
20°C13/27°C
20°C14/28°C
18°C14/23°C
17°C12/21°C
17°C11/25°C
18°C10/28°C
20°C10/29°C
20°C11/30°C
19°C11/29°C
20°C11/28°C
19°C10/28°C
16°C11/23°C
13°C10/18°C
11°C9/14°C
11°C7/15°C
10°C7/16°C
10°C5/15°C
--°C/°C
35AQI
35AQI
34AQI
33AQI
2025 Days Vs Air Quality
Chester, California, United States
98%
188
2%
4
Total number of days with different AQI categories in last 277 days in 2025 (88 days remaining)
Under WHO’s Safe Air Quality Limits: 98%
Health Risk Level:
Very Low
In 2025, 98% of 277 days were within WHO’s safe air quality limits. The risk of health issues is Very Low, but health impacts are still unclear.
Annual Air Quality Insights
Chester, California, United States
AQI levels in 2025
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
28AQI
23AQI
34AQI
35AQI
32AQI
26AQI
36AQI
41AQI
33AQI
34AQI
33AQI
32AQI
23AQI
30AQI
38AQI
39AQI
31AQI
28AQI
28AQI
32AQI
35AQI
36AQI
27AQI
24AQI
28AQI
25AQI
23AQI
30AQI
29AQI
31AQI
29AQI
28AQI
24AQI
24AQI
23AQI
24AQI
21AQI
23AQI
22AQI
20AQI
20AQI
19AQI
28AQI
22AQI
25AQI
24AQI
28AQI
36AQI
23AQI
23AQI
19AQI
20AQI
19AQI
19AQI
19AQI
18AQI
19AQI
19AQI
19AQI
23AQI
21AQI
17AQI
19AQI
23AQI
19AQI
22AQI
20AQI
21AQI
19AQI
20AQI
19AQI
25AQI
25AQI
28AQI
28AQI
29AQI
25AQI
30AQI
26AQI
24AQI
23AQI
21AQI
20AQI
23AQI
20AQI
21AQI
31AQI
24AQI
23AQI
22AQI
24AQI
27AQI
28AQI
29AQI
24AQI
23AQI
31AQI
31AQI
25AQI
29AQI
24AQI
26AQI
32AQI
44AQI
26AQI
22AQI
44AQI
52AQI
54AQI
59AQI
60AQI
43AQI
36AQI
34AQI
33AQI
32AQI
34AQI
26AQI
18AQI
18AQI
21AQI
24AQI
23AQI
24AQI
24AQI
27AQI
27AQI
22AQI
25AQI
25AQI
22AQI
23AQI
23AQI
23AQI
21AQI
23AQI
21AQI
22AQI
24AQI
27AQI
28AQI
31AQI
27AQI
26AQI
19AQI
17AQI
20AQI
21AQI
24AQI
30AQI
27AQI
34AQI
30AQI
38AQI
38AQI
32AQI
25AQI
30AQI
35AQI
28AQI
25AQI
38AQI
29AQI
36AQI
33AQI
28AQI
24AQI
18AQI
20AQI
19AQI
24AQI
26AQI
28AQI
21AQI
19AQI
24AQI
27AQI
29AQI
27AQI
26AQI
18AQI
23AQI
20AQI
37AQI
31AQI
24AQI
33AQI
23AQI
17AQI
22AQI
20AQI
24AQI
30AQI
30AQI
22AQI
24AQI
32AQI
26AQI
26AQI
22AQI
No. of days
202527AQI
Highest AQI recorded in
July32AQI
Lowest AQI recorded in
May22AQI
Most & Least Polluted Years Over the Last 1 Years
Chester's annual 2025 AQI (27) shows an average percentage change of NaN% (improved AQI) compared to previous years: .