Waterloo, Ontario, Canada 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
Waterloo, Ontario, Canada
AQI Trends: Highest and Lowest
Same Day Analysis (11th October ):
On this day, AQI across the 5 years varied significantly: 2025 ranks 1st highest AQI at 39 of Good air quality on the same day.
Download 2024 Annual Data
World Air Quality Report

Day & Night AQI Trend: 11th Oct - 12th Oct 2025
Waterloo, Ontario, Canada
7 AM11th Oct 2025
7 PM
6 AM12th Oct 2025
45AQI
16AQI
60AQI
21AQI
In the last 24 hours,
Waterloo's AQI reached its highest point of 60 at 3 AM during the Night, while the lowest point, undefined, was recorded at 6 AM during the Night between 11th Oct and 12th Oct 2025.
Day & Night AQI Trend : Sep - Oct 2025
Waterloo, Ontario, Canada
19°C10/26°C
19°C12/25°C
20°C12/28°C
19°C11/27°C
18°C11/26°C
20°C11/29°C
20°C12/28°C
16°C11/24°C
14°C11/21°C
19°C10/28°C
20°C16/24°C
21°C18/26°C
18°C16/21°C
18°C15/22°C
18°C13/26°C
19°C12/26°C
20°C14/26°C
17°C8/29°C
16°C7/26°C
13°C7/21°C
13°C5/24°C
16°C6/29°C
20°C10/31°C
20°C12/28°C
21°C14/30°C
17°C12/21°C
10°C5/15°C
7°C0/15°C
9°C-1/18°C
12°C8/17°C
--°C/°C
38AQI
38AQI
43AQI
39AQI
2025 Days Vs Air Quality
Waterloo, Ontario, Canada
84%
238
15%
43
1%
3
Total number of days with different AQI categories in last 285 days in 2025 (80 days remaining)
Under WHO’s Safe Air Quality Limits: 84%
Health Risk Level:
Low
In 2025, 84% of 285 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
Waterloo, Ontario, Canada
AQI levels in 2025
Jan.
Feb.
Mar.
Apr.
May
Jun.
Jul.
Aug.
Sep.
Oct.
Nov.
Dec.
21AQI
21AQI
24AQI
28AQI
27AQI
23AQI
24AQI
28AQI
29AQI
46AQI
63AQI
46AQI
38AQI
25AQI
24AQI
50AQI
38AQI
29AQI
27AQI
25AQI
24AQI
31AQI
40AQI
26AQI
49AQI
31AQI
27AQI
29AQI
28AQI
25AQI
54AQI
27AQI
31AQI
55AQI
27AQI
24AQI
33AQI
28AQI
38AQI
34AQI
29AQI
39AQI
26AQI
27AQI
30AQI
33AQI
29AQI
28AQI
27AQI
25AQI
22AQI
28AQI
51AQI
59AQI
54AQI
59AQI
32AQI
41AQI
26AQI
30AQI
28AQI
32AQI
36AQI
39AQI
27AQI
32AQI
33AQI
30AQI
31AQI
31AQI
27AQI
31AQI
57AQI
57AQI
25AQI
16AQI
24AQI
33AQI
24AQI
17AQI
17AQI
19AQI
21AQI
18AQI
18AQI
25AQI
28AQI
37AQI
23AQI
21AQI
17AQI
17AQI
23AQI
18AQI
19AQI
17AQI
19AQI
14AQI
18AQI
32AQI
29AQI
24AQI
37AQI
28AQI
17AQI
13AQI
19AQI
37AQI
40AQI
17AQI
22AQI
14AQI
34AQI
39AQI
35AQI
27AQI
15AQI
23AQI
33AQI
17AQI
33AQI
30AQI
18AQI
17AQI
19AQI
21AQI
36AQI
20AQI
21AQI
28AQI
25AQI
30AQI
37AQI
22AQI
31AQI
30AQI
28AQI
18AQI
15AQI
16AQI
17AQI
12AQI
11AQI
12AQI
17AQI
22AQI
28AQI
24AQI
29AQI
36AQI
28AQI
19AQI
24AQI
41AQI
73AQI
54AQI
64AQI
65AQI
82AQI
67AQI
56AQI
62AQI
67AQI
46AQI
35AQI
37AQI
38AQI
42AQI
40AQI
28AQI
38AQI
47AQI
49AQI
52AQI
55AQI
46AQI
40AQI
37AQI
32AQI
36AQI
40AQI
37AQI
40AQI
45AQI
40AQI
44AQI
51AQI
47AQI
34AQI
43AQI
38AQI
47AQI
44AQI
45AQI
46AQI
59AQI
67AQI
48AQI
25AQI
35AQI
24AQI
47AQI
23AQI
26AQI
36AQI
32AQI
57AQI
41AQI
51AQI
43AQI
51AQI
99AQI
54AQI
44AQI
105AQI
125AQI
103AQI
83AQI
86AQI
82AQI
61AQI
63AQI
61AQI
53AQI
44AQI
59AQI
70AQI
62AQI
36AQI
15AQI
21AQI
18AQI
18AQI
24AQI
30AQI
25AQI
16AQI
17AQI
20AQI
25AQI
19AQI
20AQI
35AQI
31AQI
31AQI
32AQI
27AQI
37AQI
18AQI
18AQI
19AQI
22AQI
35AQI
35AQI
38AQI
55AQI
53AQI
46AQI
39AQI
41AQI
44AQI
25AQI
19AQI
20AQI
33AQI
37AQI
43AQI
24AQI
28AQI
40AQI
23AQI
24AQI
27AQI
22AQI
21AQI
44AQI
56AQI
55AQI
54AQI
30AQI
42AQI
30AQI
19AQI
39AQI
32AQI
34AQI
29AQI
24AQI
24AQI
47AQI
44AQI
48AQI
32AQI
37AQI
No. of days
202535AQI
Highest AQI recorded in
August48AQI
Lowest AQI recorded in
May24AQI
202433AQI
Highest AQI recorded in
January37AQI
Lowest AQI recorded in
November25AQI
202342AQI
Highest AQI recorded in
June72AQI
Lowest AQI recorded in
October30AQI
202235AQI
Highest AQI recorded in
June39AQI
Lowest AQI recorded in
August17AQI
202137AQI
Highest AQI recorded in
July46AQI
Lowest AQI recorded in
October30AQI
202032AQI
Highest AQI recorded in
November35AQI
Lowest AQI recorded in
October24AQI
Most & Least Polluted Years Over the Last 6 Years
Waterloo's annual 2025 AQI (35) shows an average percentage change of -0.9% (improved AQI) compared to previous years: 2020 (32), 2021 (37), 2022 (35), 2023 (42), 2024 (33).