West Yellowstone, 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
West Yellowstone, Montana, United States
AQI Trends: Highest and Lowest
Same Day Analysis (29th September ):
On this day, AQI across the 1 years varied significantly: 2025 ranks 1st highest AQI at 22 of Good air quality on the same day.
Download 2024 Annual Data
World Air Quality Report

Day & Night AQI Trend: 29th Sep - 30th Sep 2025
West Yellowstone, Montana, United States
7 AM29th Sep 2025
7 PM
6 AM30th Sep 2025
35AQI
18AQI
34AQI
11AQI
In the last 24 hours,
West Yellowstone's AQI reached its highest point of 35 at 1 PM during the Day, while the lowest point, 11, was recorded at 10 PM during the Night between 29th Sep and 30th Sep 2025.
Day & Night AQI Trend : Aug - Sep 2025
West Yellowstone, Montana, United States
17°C9/24°C
19°C11/25°C
19°C11/26°C
20°C12/26°C
18°C12/24°C
14°C8/20°C
15°C7/22°C
16°C12/22°C
15°C9/21°C
16°C9/22°C
16°C9/22°C
13°C9/19°C
14°C8/20°C
13°C9/18°C
13°C7/18°C
10°C7/14°C
10°C5/15°C
12°C6/18°C
13°C6/20°C
14°C7/21°C
16°C10/21°C
13°C9/18°C
10°C7/12°C
10°C4/17°C
13°C6/20°C
13°C5/20°C
13°C8/17°C
13°C6/21°C
14°C8/20°C
14°C10/18°C
--°C/°C
29AQI
25AQI
26AQI
24AQI
2025 Days Vs Air Quality
West Yellowstone, Montana, United States
97%
183
3%
5
Total number of days with different AQI categories in last 273 days in 2025 (92 days remaining)
Under WHO’s Safe Air Quality Limits: 97%
Health Risk Level:
Very Low
In 2025, 97% of 273 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
West Yellowstone, Montana, United States
AQI levels in 2025
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
18AQI
18AQI
43AQI
27AQI
19AQI
19AQI
16AQI
16AQI
16AQI
15AQI
13AQI
16AQI
16AQI
19AQI
30AQI
29AQI
37AQI
22AQI
21AQI
17AQI
15AQI
19AQI
16AQI
12AQI
13AQI
14AQI
14AQI
16AQI
14AQI
15AQI
14AQI
16AQI
16AQI
15AQI
18AQI
12AQI
16AQI
18AQI
18AQI
18AQI
16AQI
14AQI
14AQI
16AQI
18AQI
18AQI
18AQI
21AQI
23AQI
17AQI
15AQI
16AQI
16AQI
15AQI
15AQI
14AQI
15AQI
20AQI
15AQI
18AQI
17AQI
17AQI
18AQI
19AQI
18AQI
19AQI
18AQI
24AQI
19AQI
15AQI
15AQI
17AQI
21AQI
22AQI
22AQI
25AQI
26AQI
21AQI
19AQI
21AQI
25AQI
28AQI
25AQI
21AQI
22AQI
24AQI
25AQI
29AQI
27AQI
18AQI
22AQI
24AQI
26AQI
25AQI
25AQI
22AQI
23AQI
27AQI
30AQI
30AQI
22AQI
36AQI
26AQI
29AQI
28AQI
28AQI
26AQI
29AQI
31AQI
30AQI
26AQI
19AQI
22AQI
28AQI
37AQI
26AQI
19AQI
22AQI
20AQI
16AQI
20AQI
24AQI
22AQI
27AQI
25AQI
25AQI
20AQI
24AQI
25AQI
20AQI
18AQI
24AQI
27AQI
23AQI
22AQI
18AQI
16AQI
17AQI
17AQI
19AQI
22AQI
26AQI
21AQI
17AQI
15AQI
15AQI
16AQI
17AQI
19AQI
21AQI
31AQI
48AQI
44AQI
52AQI
36AQI
21AQI
36AQI
38AQI
28AQI
41AQI
33AQI
43AQI
58AQI
65AQI
63AQI
45AQI
54AQI
27AQI
20AQI
14AQI
15AQI
12AQI
14AQI
15AQI
14AQI
14AQI
15AQI
17AQI
18AQI
16AQI
14AQI
13AQI
13AQI
22AQI
24AQI
22AQI
15AQI
22AQI
24AQI
17AQI
17AQI
23AQI
26AQI
25AQI
26AQI
No. of days
202522AQI
Highest AQI recorded in
September26AQI
Lowest AQI recorded in
May17AQI
Most & Least Polluted Years Over the Last 1 Years
West Yellowstone's annual 2025 AQI (22) shows an average percentage change of NaN% (improved AQI) compared to previous years: .