St Thomas, Ontario, Canada 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
St Thomas, Ontario, Canada
AQI Trends: Highest and Lowest
Same Day Analysis (28th September):
On this day, AQI across the 5 years varied significantly: 2026 ranks 4th highest AQI at 25 of Good air quality, showing improvement over 2025, 2023 and 2022 on the same day.
Day & Night AQI Trend: 27th Sep - 28th Sep 2026
St Thomas, Ontario, Canada
7 AM27th Sep 2026
7 PM
6 AM28th Sep 2026
53AQI
34AQI
32AQI
21AQI
In the last 24 hours,
St Thomas's AQI reached its highest point of 53 at 5 PM during the Day, while the lowest point, 21, was recorded at 12 AM during the Night between 27th Sep and 28th Sep 2026.
Day & Night AQI Trend : Aug - Sep 2026
St Thomas, Ontario, Canada
21°C19/24°C
24°C20/28°C
26°C21/32°C
26°C22/32°C
24°C19/29°C
21°C17/25°C
20°C17/26°C
18°C13/24°C
18°C12/24°C
19°C12/24°C
23°C20/27°C
21°C18/26°C
18°C11/24°C
20°C15/25°C
21°C15/26°C
16°C13/20°C
20°C18/24°C
21°C20/23°C
20°C18/22°C
18°C14/22°C
17°C16/19°C
17°C14/19°C
14°C12/16°C
15°C11/18°C
16°C14/18°C
16°C14/17°C
15°C12/17°C
16°C12/20°C
17°C14/21°C
16°C13/19°C
34AQI
30AQI
34AQI
30AQI
2026 Days Vs Air Quality
St Thomas, Ontario, Canada
85%
227
14%
37
1%
3
0.3%
1
Total number of days with different AQI categories in last 271 days in 2026 (94 days remaining)
Under WHO’s Safe Air Quality Limits: 85%
Health Risk Level:
Low
In 2026, 85% of 271 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
St Thomas, Ontario, Canada
AQI levels in 2026
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
9AQI (US)
11AQI (US)
19AQI (US)
20AQI (US)
59AQI (US)
83AQI (US)
50AQI (US)
49AQI (US)
20AQI (US)
16AQI (US)
15AQI (US)
20AQI (US)
30AQI (US)
24AQI (US)
12AQI (US)
17AQI (US)
33AQI (US)
21AQI (US)
29AQI (US)
23AQI (US)
23AQI (US)
52AQI (US)
60AQI (US)
48AQI (US)
50AQI (US)
48AQI (US)
43AQI (US)
42AQI (US)
49AQI (US)
59AQI (US)
42AQI (US)
46AQI (US)
74AQI (US)
73AQI (US)
44AQI (US)
54AQI (US)
76AQI (US)
39AQI (US)
42AQI (US)
46AQI (US)
47AQI (US)
38AQI (US)
38AQI (US)
51AQI (US)
83AQI (US)
79AQI (US)
102AQI (US)
114AQI (US)
62AQI (US)
46AQI (US)
50AQI (US)
41AQI (US)
33AQI (US)
39AQI (US)
43AQI (US)
58AQI (US)
31AQI (US)
71AQI (US)
38AQI (US)
37AQI (US)
50AQI (US)
58AQI (US)
95AQI (US)
75AQI (US)
58AQI (US)
80AQI (US)
35AQI (US)
34AQI (US)
59AQI (US)
44AQI (US)
38AQI (US)
43AQI (US)
35AQI (US)
32AQI (US)
37AQI (US)
34AQI (US)
36AQI (US)
64AQI (US)
81AQI (US)
40AQI (US)
58AQI (US)
39AQI (US)
34AQI (US)
45AQI (US)
61AQI (US)
29AQI (US)
31AQI (US)
35AQI (US)
42AQI (US)
66AQI (US)
30AQI (US)
30AQI (US)
39AQI (US)
28AQI (US)
31AQI (US)
27AQI (US)
27AQI (US)
37AQI (US)
49AQI (US)
33AQI (US)
30AQI (US)
47AQI (US)
46AQI (US)
48AQI (US)
41AQI (US)
50AQI (US)
40AQI (US)
33AQI (US)
29AQI (US)
33AQI (US)
37AQI (US)
27AQI (US)
28AQI (US)
32AQI (US)
27AQI (US)
30AQI (US)
28AQI (US)
26AQI (US)
26AQI (US)
23AQI (US)
30AQI (US)
32AQI (US)
40AQI (US)
39AQI (US)
27AQI (US)
34AQI (US)
30AQI (US)
27AQI (US)
28AQI (US)
42AQI (US)
22AQI (US)
40AQI (US)
56AQI (US)
65AQI (US)
63AQI (US)
44AQI (US)
49AQI (US)
44AQI (US)
44AQI (US)
51AQI (US)
40AQI (US)
44AQI (US)
32AQI (US)
29AQI (US)
24AQI (US)
24AQI (US)
23AQI (US)
28AQI (US)
32AQI (US)
28AQI (US)
38AQI (US)
28AQI (US)
27AQI (US)
25AQI (US)
24AQI (US)
26AQI (US)
26AQI (US)
27AQI (US)
27AQI (US)
26AQI (US)
24AQI (US)
23AQI (US)
25AQI (US)
27AQI (US)
27AQI (US)
27AQI (US)
24AQI (US)
24AQI (US)
20AQI (US)
23AQI (US)
24AQI (US)
24AQI (US)
38AQI (US)
27AQI (US)
33AQI (US)
28AQI (US)
26AQI (US)
30AQI (US)
48AQI (US)
60AQI (US)
39AQI (US)
26AQI (US)
30AQI (US)
29AQI (US)
32AQI (US)
28AQI (US)
29AQI (US)
32AQI (US)
35AQI (US)
44AQI (US)
45AQI (US)
31AQI (US)
56AQI (US)
89AQI (US)
212AQI (US)
117AQI (US)
86AQI (US)
79AQI (US)
65AQI (US)
23AQI (US)
25AQI (US)
31AQI (US)
24AQI (US)
33AQI (US)
50AQI (US)
57AQI (US)
24AQI (US)
33AQI (US)
31AQI (US)
47AQI (US)
34AQI (US)
31AQI (US)
32AQI (US)
36AQI (US)
35AQI (US)
31AQI (US)
31AQI (US)
32AQI (US)
36AQI (US)
31AQI (US)
35AQI (US)
38AQI (US)
34AQI (US)
27AQI (US)
26AQI (US)
30AQI (US)
31AQI (US)
29AQI (US)
34AQI (US)
35AQI (US)
27AQI (US)
29AQI (US)
35AQI (US)
28AQI (US)
27AQI (US)
33AQI (US)
25AQI (US)
32AQI (US)
25AQI (US)
34AQI (US)
45AQI (US)
39AQI (US)
27AQI (US)
32AQI (US)
27AQI (US)
36AQI (US)
31AQI (US)
35AQI (US)
29AQI (US)
30AQI (US)
39AQI (US)
35AQI (US)
42AQI (US)
36AQI (US)
36AQI (US)
28AQI (US)
30AQI (US)
34AQI (US)
30AQI (US)
30AQI (US)
27AQI (US)
27AQI (US)
30AQI (US)
28AQI (US)
35AQI (US)
39AQI (US)
37AQI (US)
25AQI (US)
35AQI (US)
56AQI (US)
49AQI (US)
34AQI (US)
37AQI (US)
27AQI (US)
50AQI (US)
32AQI (US)
33AQI (US)
No. of days
202639AQI (US)
Highest AQI (US) recorded in
February56AQI (US)
Lowest AQI (US) recorded in
June27AQI (US)
202534AQI (US)
Highest AQI (US) recorded in
August49AQI (US)
Lowest AQI (US) recorded in
May22AQI (US)
202433AQI (US)
Highest AQI (US) recorded in
January37AQI (US)
Lowest AQI (US) recorded in
November26AQI (US)
202341AQI (US)
Highest AQI (US) recorded in
June73AQI (US)
Lowest AQI (US) recorded in
October30AQI (US)
202233AQI (US)
Highest AQI (US) recorded in
June37AQI (US)
Lowest AQI (US) recorded in
August21AQI (US)
202136AQI (US)
Highest AQI (US) recorded in
July48AQI (US)
Lowest AQI (US) recorded in
November27AQI (US)
202033AQI (US)
Highest AQI (US) recorded in
June37AQI (US)
Lowest AQI (US) recorded in
October28AQI (US)
Most & Least Polluted Years Over the Last 7 Years
St Thomas's annual 2026 AQI (US) (39) shows an average percentage change of 12.1% (worsened AQI (US)) compared to previous years: 2020 (33), 2021 (36), 2022 (33), 2023 (41), 2024 (33), 2025 (34).