Hamilton, Montana, 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
Hamilton, Montana, United States
AQI Trends: Highest and Lowest
Same Day Analysis (30th September ):
On this day, AQI across the 5 years varied significantly: 2025 ranks 2nd highest AQI at 25 of Good air quality, showing improvement over 2021 on the same day.
Download 2024 Annual Data
World Air Quality Report

2025 Days Vs Air Quality
Hamilton, Montana, United States
94%
256
6%
17
Total number of days with different AQI categories in last 274 days in 2025 (91 days remaining)
Under WHO’s Safe Air Quality Limits: 94%
Health Risk Level:
Very Low
In 2025, 94% of 274 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
Hamilton, Montana, United States
AQI levels in 2025
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
23AQI
36AQI
50AQI
41AQI
27AQI
38AQI
37AQI
47AQI
56AQI
33AQI
25AQI
29AQI
27AQI
35AQI
54AQI
54AQI
21AQI
27AQI
40AQI
32AQI
43AQI
26AQI
37AQI
36AQI
31AQI
32AQI
44AQI
49AQI
56AQI
62AQI
47AQI
20AQI
23AQI
24AQI
22AQI
25AQI
29AQI
32AQI
33AQI
28AQI
28AQI
41AQI
48AQI
47AQI
39AQI
21AQI
18AQI
30AQI
19AQI
25AQI
35AQI
16AQI
16AQI
12AQI
12AQI
12AQI
17AQI
18AQI
17AQI
22AQI
19AQI
28AQI
24AQI
14AQI
19AQI
15AQI
12AQI
13AQI
12AQI
14AQI
15AQI
21AQI
16AQI
17AQI
15AQI
15AQI
19AQI
19AQI
14AQI
23AQI
15AQI
16AQI
15AQI
19AQI
24AQI
18AQI
19AQI
17AQI
18AQI
18AQI
17AQI
21AQI
18AQI
18AQI
21AQI
22AQI
21AQI
14AQI
17AQI
28AQI
29AQI
18AQI
19AQI
26AQI
25AQI
31AQI
16AQI
20AQI
19AQI
15AQI
12AQI
15AQI
20AQI
21AQI
19AQI
28AQI
21AQI
18AQI
16AQI
15AQI
20AQI
24AQI
35AQI
15AQI
15AQI
20AQI
17AQI
14AQI
16AQI
16AQI
15AQI
15AQI
14AQI
14AQI
13AQI
13AQI
12AQI
13AQI
12AQI
12AQI
13AQI
13AQI
12AQI
17AQI
16AQI
17AQI
17AQI
17AQI
16AQI
15AQI
16AQI
17AQI
14AQI
15AQI
17AQI
17AQI
25AQI
29AQI
35AQI
28AQI
20AQI
25AQI
21AQI
18AQI
20AQI
23AQI
24AQI
19AQI
19AQI
20AQI
19AQI
17AQI
15AQI
19AQI
29AQI
22AQI
19AQI
19AQI
16AQI
16AQI
19AQI
25AQI
26AQI
23AQI
19AQI
31AQI
21AQI
19AQI
20AQI
20AQI
18AQI
18AQI
22AQI
20AQI
21AQI
20AQI
28AQI
30AQI
29AQI
26AQI
22AQI
25AQI
17AQI
20AQI
27AQI
29AQI
33AQI
23AQI
19AQI
18AQI
20AQI
21AQI
24AQI
24AQI
28AQI
27AQI
24AQI
28AQI
23AQI
17AQI
16AQI
17AQI
19AQI
22AQI
22AQI
30AQI
29AQI
26AQI
17AQI
21AQI
28AQI
37AQI
44AQI
47AQI
49AQI
54AQI
56AQI
58AQI
44AQI
37AQI
45AQI
45AQI
56AQI
51AQI
50AQI
60AQI
69AQI
77AQI
81AQI
78AQI
37AQI
48AQI
50AQI
22AQI
19AQI
23AQI
30AQI
18AQI
17AQI
27AQI
28AQI
27AQI
26AQI
26AQI
19AQI
27AQI
22AQI
46AQI
55AQI
60AQI
50AQI
29AQI
25AQI
39AQI
25AQI
18AQI
20AQI
16AQI
21AQI
23AQI
33AQI
40AQI
No. of days
202526AQI
Highest AQI recorded in
September40AQI
Lowest AQI recorded in
May16AQI
202429AQI
Highest AQI recorded in
September52AQI
Lowest AQI recorded in
May11AQI
202324AQI
Highest AQI recorded in
November38AQI
Lowest AQI recorded in
June15AQI
202230AQI
Highest AQI recorded in
September83AQI
Lowest AQI recorded in
May13AQI
202133AQI
Highest AQI recorded in
July95AQI
Lowest AQI recorded in
May15AQI
202027AQI
Highest AQI recorded in
September64AQI
Lowest AQI recorded in
June11AQI
Most & Least Polluted Years Over the Last 6 Years
Hamilton's annual 2025 AQI (26) shows an average percentage change of -7.9% (improved AQI) compared to previous years: 2020 (27), 2021 (33), 2022 (30), 2023 (24), 2024 (29).