Country Background
HistoryAQIPM2.5PM10COSO2NO2O3

St Catharines, Ontario, Canada Historical Air Quality Analysis

Dive into detailed Air Quality Insights with historical data, monthly patterns, and yearly trends at your fingertips!

Good
050
Moderate
100
Poor
150
Unhealthy
200
Severe
300
Hazardous
301+

August Air Quality Analysis

St Catharines, Ontario, Canada

2021
2022
2023
2024
2025
AQI
.
Days

AQI Trends: Highest and Lowest

Highest AQI recorded on
16th Aug 2023
78AQI
Lowest AQI recorded on
18th Aug 2021
17AQI

Same Day Analysis (1st August ):
On this day, AQI across the 5 years varied significantly: 2025 ranks 1st highest AQI at 55 of Moderate air quality on the same day.

Download 2024 Annual Data

World Air Quality Report

Globe

Day & Night AQI Trend: 1st Aug - 2nd Aug 2025

St Catharines, Ontario, Canada

AQI
Day
Night
.

5 AM1st Aug 2025

8 PM

4 AM2nd Aug 2025

Day time
Avg. Highest Time
6AM1st Aug

64AQI

Avg. Lowest Time
8PM1st Aug

20AQI

Night time
Avg. Highest Time
5AM1st Aug

72AQI

Avg. Lowest Time
11PM1st Aug

24AQI

In the last 24 hours,

St Catharines's AQI reached its highest point of 72 at 5 AM during the Night, while the lowest point, 20, was recorded at 8 PM during the Day between 1st Aug and 2nd Aug 2025.

Day & Night AQI Trend : Jul - Aug 2025

St Catharines, Ontario, Canada

JulAug
03rd - 04th04th - 05th05th - 06th06th - 07th07th - 08th08th - 09th09th - 10th10th - 11th11th - 12th12th - 13th13th - 14th14th - 15th15th - 16th16th - 17th17th - 18th18th - 19th19th - 20th20th - 21st21st - 22nd22nd - 23rd23rd - 24th24th - 25th25th - 26th26th - 27th27th - 28th28th - 29th29th - 30th30th - 31st31st - 01st01st - 02nd02nd
Day
Night
3rd Jul 2025445 AMAQI
3rd Jul 2025376 AMAQI
3rd Jul 2025397 AMAQI
3rd Jul 2025408 AMAQI
3rd Jul 2025409 AMAQI
3rd Jul 20254310 AMAQI
3rd Jul 20254911 AMAQI
3rd Jul 20255312 PMAQI
3rd Jul 2025541 PMAQI
3rd Jul 2025542 PMAQI
3rd Jul 2025553 PMAQI
3rd Jul 2025544 PMAQI
3rd Jul 2025525 PMAQI
3rd Jul 2025526 PMAQI
3rd Jul 2025517 PMAQI
3rd Jul 2025528 PMAQI
3rd Jul 2025499 PMAQI
3rd Jul 20254810 PMAQI
3rd Jul 20254211 PMAQI
4th Jul 20254112 AMAQI
4th Jul 2025411 AMAQI
4th Jul 2025302 AMAQI
4th Jul 2025243 AMAQI
4th Jul 2025264 AMAQI

22°C18/27°C

4th Jul 2025285 AMAQI
4th Jul 2025286 AMAQI
4th Jul 2025287 AMAQI
4th Jul 2025308 AMAQI
4th Jul 2025319 AMAQI
4th Jul 20252910 AMAQI
4th Jul 20252811 AMAQI
4th Jul 20252712 PMAQI
4th Jul 2025291 PMAQI
4th Jul 2025272 PMAQI
4th Jul 2025283 PMAQI
4th Jul 2025284 PMAQI
4th Jul 2025315 PMAQI
4th Jul 2025306 PMAQI
4th Jul 2025307 PMAQI
4th Jul 2025308 PMAQI
4th Jul 2025309 PMAQI
4th Jul 20253210 PMAQI
4th Jul 20253611 PMAQI
5th Jul 20254612 AMAQI
5th Jul 2025471 AMAQI
5th Jul 2025522 AMAQI
5th Jul 2025543 AMAQI
5th Jul 2025774 AMAQI

20°C15/25°C

5th Jul 2025605 AMAQI
5th Jul 2025486 AMAQI
5th Jul 2025507 AMAQI
5th Jul 2025528 AMAQI
5th Jul 2025549 AMAQI
5th Jul 20255510 AMAQI
5th Jul 20255611 AMAQI
5th Jul 20255612 PMAQI
5th Jul 2025581 PMAQI
5th Jul 2025582 PMAQI
5th Jul 2025563 PMAQI
5th Jul 2025574 PMAQI
5th Jul 2025545 PMAQI
5th Jul 2025536 PMAQI
5th Jul 2025527 PMAQI
5th Jul 2025528 PMAQI
5th Jul 2025539 PMAQI
5th Jul 20255310 PMAQI
5th Jul 20255111 PMAQI
6th Jul 20255312 AMAQI
6th Jul 2025521 AMAQI
6th Jul 2025482 AMAQI
6th Jul 2025473 AMAQI
6th Jul 2025454 AMAQI

24°C15/33°C

6th Jul 2025505 AMAQI
6th Jul 2025516 AMAQI
6th Jul 2025537 AMAQI
6th Jul 2025518 AMAQI
6th Jul 2025529 AMAQI
6th Jul 20255210 AMAQI
6th Jul 20255111 AMAQI
6th Jul 20255212 PMAQI
6th Jul 2025511 PMAQI
6th Jul 2025512 PMAQI
6th Jul 2025513 PMAQI
6th Jul 2025524 PMAQI
6th Jul 2025525 PMAQI
6th Jul 2025526 PMAQI
6th Jul 2025527 PMAQI
6th Jul 2025528 PMAQI
6th Jul 2025529 PMAQI
6th Jul 20255210 PMAQI
6th Jul 20255111 PMAQI
7th Jul 20255212 AMAQI
7th Jul 2025531 AMAQI
7th Jul 2025522 AMAQI
7th Jul 2025523 AMAQI
7th Jul 2025524 AMAQI

27°C22/34°C

7th Jul 2025525 AMAQI
7th Jul 2025516 AMAQI
7th Jul 2025517 AMAQI
7th Jul 2025528 AMAQI
7th Jul 2025529 AMAQI
7th Jul 20255210 AMAQI
7th Jul 20255211 AMAQI
7th Jul 20255212 PMAQI
7th Jul 2025501 PMAQI
7th Jul 2025482 PMAQI
7th Jul 2025373 PMAQI
7th Jul 2025404 PMAQI
7th Jul 2025435 PMAQI
7th Jul 2025416 PMAQI
7th Jul 2025407 PMAQI
7th Jul 2025398 PMAQI
7th Jul 2025429 PMAQI
7th Jul 20253710 PMAQI
7th Jul 20253911 PMAQI
8th Jul 20253812 AMAQI
8th Jul 2025391 AMAQI
8th Jul 2025372 AMAQI
8th Jul 2025283 AMAQI
8th Jul 2025244 AMAQI

25°C21/28°C

8th Jul 2025255 AMAQI
8th Jul 2025246 AMAQI
8th Jul 2025247 AMAQI
8th Jul 2025248 AMAQI
8th Jul 2025259 AMAQI
8th Jul 20252310 AMAQI
8th Jul 20252311 AMAQI
8th Jul 20252412 PMAQI
8th Jul 2025241 PMAQI
8th Jul 2025272 PMAQI
8th Jul 2025273 PMAQI
8th Jul 2025284 PMAQI
8th Jul 2025305 PMAQI
8th Jul 2025306 PMAQI
8th Jul 2025307 PMAQI
8th Jul 2025288 PMAQI
8th Jul 2025289 PMAQI
8th Jul 20252710 PMAQI
8th Jul 20252711 PMAQI
9th Jul 20252712 AMAQI
9th Jul 2025271 AMAQI
9th Jul 2025262 AMAQI
9th Jul 2025263 AMAQI
9th Jul 2025274 AMAQI

22°C19/26°C

9th Jul 2025355 AMAQI
9th Jul 2025366 AMAQI
9th Jul 2025387 AMAQI
9th Jul 2025328 AMAQI
9th Jul 2025349 AMAQI
9th Jul 20254210 AMAQI
9th Jul 20254011 AMAQI
9th Jul 20254412 PMAQI
9th Jul 2025431 PMAQI
9th Jul 2025442 PMAQI
9th Jul 2025443 PMAQI
9th Jul 2025454 PMAQI
9th Jul 2025465 PMAQI
9th Jul 2025466 PMAQI
9th Jul 2025457 PMAQI
9th Jul 2025448 PMAQI
9th Jul 2025409 PMAQI
9th Jul 20254110 PMAQI
9th Jul 20254111 PMAQI
10th Jul 20254112 AMAQI
10th Jul 2025421 AMAQI
10th Jul 2025422 AMAQI
10th Jul 2025443 AMAQI
10th Jul 2025524 AMAQI

22°C18/25°C

10th Jul 2025515 AMAQI
10th Jul 2025486 AMAQI
10th Jul 2025467 AMAQI
10th Jul 2025448 AMAQI
10th Jul 2025479 AMAQI
10th Jul 20254610 AMAQI
10th Jul 20254311 AMAQI
10th Jul 20254512 PMAQI
10th Jul 2025471 PMAQI
10th Jul 2025472 PMAQI
10th Jul 2025473 PMAQI
10th Jul 2025444 PMAQI
10th Jul 2025485 PMAQI
10th Jul 2025466 PMAQI
10th Jul 2025487 PMAQI
10th Jul 2025468 PMAQI
10th Jul 2025469 PMAQI
10th Jul 20254410 PMAQI
10th Jul 20255011 PMAQI
11th Jul 20254612 AMAQI
11th Jul 2025481 AMAQI
11th Jul 2025542 AMAQI
11th Jul 2025533 AMAQI
11th Jul 2025544 AMAQI

23°C18/28°C

11th Jul 2025545 AMAQI
11th Jul 2025556 AMAQI
11th Jul 2025547 AMAQI
11th Jul 2025548 AMAQI
11th Jul 2025539 AMAQI
11th Jul 20255410 AMAQI
11th Jul 20255411 AMAQI
11th Jul 20255412 PMAQI
11th Jul 2025541 PMAQI
11th Jul 2025542 PMAQI
11th Jul 2025533 PMAQI
11th Jul 2025534 PMAQI
11th Jul 2025525 PMAQI
11th Jul 2025526 PMAQI
11th Jul 2025527 PMAQI
11th Jul 2025528 PMAQI
11th Jul 2025529 PMAQI
11th Jul 20255210 PMAQI
11th Jul 20255111 PMAQI
12th Jul 20255312 AMAQI
12th Jul 2025511 AMAQI
12th Jul 2025532 AMAQI
12th Jul 2025503 AMAQI
12th Jul 2025454 AMAQI

24°C19/30°C

12th Jul 2025415 AMAQI
12th Jul 2025386 AMAQI
12th Jul 2025377 AMAQI
12th Jul 2025378 AMAQI
12th Jul 2025379 AMAQI
12th Jul 20253210 AMAQI
12th Jul 20253411 AMAQI
12th Jul 20253412 PMAQI
12th Jul 2025371 PMAQI
12th Jul 2025392 PMAQI
12th Jul 2025443 PMAQI
12th Jul 2025424 PMAQI
12th Jul 2025435 PMAQI
12th Jul 2025466 PMAQI
12th Jul 2025467 PMAQI
12th Jul 2025458 PMAQI
12th Jul 2025449 PMAQI
12th Jul 20254310 PMAQI
12th Jul 20254411 PMAQI
13th Jul 20254412 AMAQI
13th Jul 2025451 AMAQI
13th Jul 2025432 AMAQI
13th Jul 2025393 AMAQI
13th Jul 2025384 AMAQI

27°C20/35°C

13th Jul 2025365 AMAQI
13th Jul 2025376 AMAQI
13th Jul 2025367 AMAQI
13th Jul 2025408 AMAQI
13th Jul 2025409 AMAQI
13th Jul 20253910 AMAQI
13th Jul 20253811 AMAQI
13th Jul 20253812 PMAQI
13th Jul 2025381 PMAQI
13th Jul 2025382 PMAQI
13th Jul 2025363 PMAQI
13th Jul 2025364 PMAQI
13th Jul 2025395 PMAQI
13th Jul 2025386 PMAQI
13th Jul 2025387 PMAQI
13th Jul 2025388 PMAQI
13th Jul 2025389 PMAQI
13th Jul 20254010 PMAQI
13th Jul 20253811 PMAQI
14th Jul 20254012 AMAQI
14th Jul 2025391 AMAQI
14th Jul 2025522 AMAQI
14th Jul 2025523 AMAQI
14th Jul 2025554 AMAQI

26°C23/30°C

14th Jul 2025445 AMAQI
14th Jul 2025346 AMAQI
14th Jul 2025477 AMAQI
14th Jul 2025488 AMAQI
14th Jul 2025489 AMAQI
14th Jul 20254510 AMAQI
14th Jul 20255011 AMAQI
14th Jul 20255312 PMAQI
14th Jul 2025551 PMAQI
14th Jul 2025552 PMAQI
14th Jul 2025533 PMAQI
14th Jul 2025504 PMAQI
14th Jul 2025515 PMAQI
14th Jul 2025516 PMAQI
14th Jul 2025527 PMAQI
14th Jul 2025518 PMAQI
14th Jul 2025509 PMAQI
14th Jul 20255010 PMAQI
14th Jul 20255011 PMAQI
15th Jul 20255112 AMAQI
15th Jul 2025571 AMAQI
15th Jul 2025582 AMAQI
15th Jul 2025603 AMAQI
15th Jul 2025624 AMAQI

25°C21/30°C

15th Jul 2025625 AMAQI
15th Jul 2025636 AMAQI
15th Jul 2025617 AMAQI
15th Jul 2025618 AMAQI
15th Jul 2025639 AMAQI
15th Jul 20256310 AMAQI
15th Jul 20256211 AMAQI
15th Jul 20256112 PMAQI
15th Jul 2025591 PMAQI
15th Jul 2025582 PMAQI
15th Jul 2025613 PMAQI
15th Jul 2025604 PMAQI
15th Jul 2025605 PMAQI
15th Jul 2025606 PMAQI
15th Jul 2025597 PMAQI
15th Jul 2025598 PMAQI
15th Jul 2025589 PMAQI
15th Jul 20255910 PMAQI
15th Jul 20256011 PMAQI
16th Jul 20255812 AMAQI
16th Jul 2025591 AMAQI
16th Jul 2025572 AMAQI
16th Jul 2025543 AMAQI
16th Jul 2025584 AMAQI

26°C20/32°C

16th Jul 2025555 AMAQI
16th Jul 2025586 AMAQI
16th Jul 2025627 AMAQI
16th Jul 2025638 AMAQI
16th Jul 2025679 AMAQI
16th Jul 20257410 AMAQI
16th Jul 20256811 AMAQI
16th Jul 20256612 PMAQI
16th Jul 2025671 PMAQI
16th Jul 2025662 PMAQI
16th Jul 2025643 PMAQI
16th Jul 2025634 PMAQI
16th Jul 2025635 PMAQI
16th Jul 2025636 PMAQI
16th Jul 2025627 PMAQI
16th Jul 2025608 PMAQI
16th Jul 2025609 PMAQI
16th Jul 20255810 PMAQI
16th Jul 20255411 PMAQI
17th Jul 20255412 AMAQI
17th Jul 2025541 AMAQI
17th Jul 2025432 AMAQI
17th Jul 2025363 AMAQI
17th Jul 2025304 AMAQI

25°C19/33°C

17th Jul 2025245 AMAQI
17th Jul 2025246 AMAQI
17th Jul 2025237 AMAQI
17th Jul 2025278 AMAQI
17th Jul 2025309 AMAQI
17th Jul 20253210 AMAQI
17th Jul 20253211 AMAQI
17th Jul 20253012 PMAQI
17th Jul 2025311 PMAQI
17th Jul 2025302 PMAQI
17th Jul 2025243 PMAQI
17th Jul 2025264 PMAQI
17th Jul 2025305 PMAQI
17th Jul 2025316 PMAQI
17th Jul 2025297 PMAQI
17th Jul 2025288 PMAQI
17th Jul 2025299 PMAQI
17th Jul 20253110 PMAQI
17th Jul 20252811 PMAQI
18th Jul 20252612 AMAQI
18th Jul 2025251 AMAQI
18th Jul 2025212 AMAQI
18th Jul 2025193 AMAQI
18th Jul 2025204 AMAQI

25°C20/30°C

18th Jul 2025205 AMAQI
18th Jul 2025206 AMAQI
18th Jul 2025207 AMAQI
18th Jul 2025208 AMAQI
18th Jul 2025199 AMAQI
18th Jul 20251910 AMAQI
18th Jul 20251911 AMAQI
18th Jul 20251912 PMAQI
18th Jul 2025191 PMAQI
18th Jul 2025192 PMAQI
18th Jul 2025193 PMAQI
18th Jul 2025194 PMAQI
18th Jul 2025195 PMAQI
18th Jul 2025196 PMAQI
18th Jul 2025197 PMAQI
18th Jul 2025208 PMAQI
18th Jul 2025199 PMAQI
18th Jul 20251910 PMAQI
18th Jul 20251911 PMAQI
19th Jul 20252012 AMAQI
19th Jul 2025241 AMAQI
19th Jul 2025272 AMAQI
19th Jul 2025283 AMAQI
19th Jul 2025264 AMAQI

21°C15/26°C

19th Jul 2025265 AMAQI
19th Jul 2025296 AMAQI
19th Jul 2025417 AMAQI
19th Jul 2025408 AMAQI
19th Jul 2025349 AMAQI
19th Jul 20253210 AMAQI
19th Jul 20253111 AMAQI
19th Jul 20252712 PMAQI
19th Jul 2025241 PMAQI
19th Jul 2025232 PMAQI
19th Jul 2025243 PMAQI
19th Jul 2025234 PMAQI
19th Jul 2025245 PMAQI
19th Jul 2025266 PMAQI
19th Jul 2025267 PMAQI
19th Jul 2025278 PMAQI
19th Jul 2025279 PMAQI
19th Jul 20252810 PMAQI
19th Jul 20252611 PMAQI
20th Jul 20252612 AMAQI
20th Jul 2025271 AMAQI
20th Jul 2025222 AMAQI
20th Jul 2025223 AMAQI
20th Jul 2025224 AMAQI

21°C13/29°C

20th Jul 2025225 AMAQI
20th Jul 2025226 AMAQI
20th Jul 2025237 AMAQI
20th Jul 2025238 AMAQI
20th Jul 2025229 AMAQI
20th Jul 20252210 AMAQI
20th Jul 20252111 AMAQI
20th Jul 20252212 PMAQI
20th Jul 2025251 PMAQI
20th Jul 2025242 PMAQI
20th Jul 2025243 PMAQI
20th Jul 2025244 PMAQI
20th Jul 2025245 PMAQI
20th Jul 2025246 PMAQI
20th Jul 2025257 PMAQI
20th Jul 2025248 PMAQI
20th Jul 2025239 PMAQI
20th Jul 20252410 PMAQI
20th Jul 20253011 PMAQI
21st Jul 20253412 AMAQI
21st Jul 2025381 AMAQI
21st Jul 2025522 AMAQI
21st Jul 2025443 AMAQI
21st Jul 2025494 AMAQI

22°C20/28°C

21st Jul 2025565 AMAQI
21st Jul 2025586 AMAQI
21st Jul 2025587 AMAQI
21st Jul 2025588 AMAQI
21st Jul 2025569 AMAQI
21st Jul 20255610 AMAQI
21st Jul 20255611 AMAQI
21st Jul 20255212 PMAQI
21st Jul 2025461 PMAQI
21st Jul 2025372 PMAQI
21st Jul 2025343 PMAQI
21st Jul 2025384 PMAQI
21st Jul 2025385 PMAQI
21st Jul 2025376 PMAQI
21st Jul 2025387 PMAQI
21st Jul 2025388 PMAQI
21st Jul 2025469 PMAQI
21st Jul 20254610 PMAQI
21st Jul 20253611 PMAQI
22nd Jul 20254012 AMAQI
22nd Jul 2025431 AMAQI
22nd Jul 2025402 AMAQI
22nd Jul 2025443 AMAQI
22nd Jul 2025364 AMAQI

20°C17/24°C

22nd Jul 2025325 AMAQI
22nd Jul 2025296 AMAQI
22nd Jul 2025257 AMAQI
22nd Jul 2025268 AMAQI
22nd Jul 2025289 AMAQI
22nd Jul 20252810 AMAQI
22nd Jul 20252411 AMAQI
22nd Jul 20252312 PMAQI
22nd Jul 2025221 PMAQI
22nd Jul 2025222 PMAQI
22nd Jul 2025243 PMAQI
22nd Jul 2025234 PMAQI
22nd Jul 2025255 PMAQI
22nd Jul 2025266 PMAQI
22nd Jul 2025247 PMAQI
22nd Jul 2025258 PMAQI
22nd Jul 2025259 PMAQI
22nd Jul 20252510 PMAQI
22nd Jul 20252411 PMAQI
23rd Jul 20252412 AMAQI
23rd Jul 2025251 AMAQI
23rd Jul 2025262 AMAQI
23rd Jul 2025233 AMAQI
23rd Jul 2025224 AMAQI

20°C14/26°C

23rd Jul 2025215 AMAQI
23rd Jul 2025206 AMAQI
23rd Jul 2025217 AMAQI
23rd Jul 2025248 AMAQI
23rd Jul 2025269 AMAQI
23rd Jul 20252610 AMAQI
23rd Jul 20252211 AMAQI
23rd Jul 20252312 PMAQI
23rd Jul 2025221 PMAQI
23rd Jul 2025222 PMAQI
23rd Jul 2025263 PMAQI
23rd Jul 2025254 PMAQI
23rd Jul 2025245 PMAQI
23rd Jul 2025276 PMAQI
23rd Jul 2025257 PMAQI
23rd Jul 2025258 PMAQI
23rd Jul 2025249 PMAQI
23rd Jul 20252410 PMAQI
23rd Jul 20252711 PMAQI
24th Jul 20252812 AMAQI
24th Jul 2025291 AMAQI
24th Jul 2025312 AMAQI
24th Jul 2025383 AMAQI
24th Jul 2025364 AMAQI

23°C14/30°C

24th Jul 2025385 AMAQI
24th Jul 2025406 AMAQI
24th Jul 2025447 AMAQI
24th Jul 2025448 AMAQI
24th Jul 2025449 AMAQI
24th Jul 20254610 AMAQI
24th Jul 20254511 AMAQI
24th Jul 20254612 PMAQI
24th Jul 2025461 PMAQI
24th Jul 2025482 PMAQI
24th Jul 2025483 PMAQI
24th Jul 2025464 PMAQI
24th Jul 2025485 PMAQI
24th Jul 2025486 PMAQI
24th Jul 2025467 PMAQI
24th Jul 2025438 PMAQI
24th Jul 2025439 PMAQI
24th Jul 20254410 PMAQI
24th Jul 20254411 PMAQI
25th Jul 20254212 AMAQI
25th Jul 2025401 AMAQI
25th Jul 2025322 AMAQI
25th Jul 2025293 AMAQI
25th Jul 2025284 AMAQI

26°C19/34°C

25th Jul 2025275 AMAQI
25th Jul 2025286 AMAQI
25th Jul 2025307 AMAQI
25th Jul 2025328 AMAQI
25th Jul 2025329 AMAQI
25th Jul 20253310 AMAQI
25th Jul 20253411 AMAQI
25th Jul 20253212 PMAQI
25th Jul 2025321 PMAQI
25th Jul 2025322 PMAQI
25th Jul 2025333 PMAQI
25th Jul 2025324 PMAQI
25th Jul 2025315 PMAQI
25th Jul 2025326 PMAQI
25th Jul 2025337 PMAQI
25th Jul 2025328 PMAQI
25th Jul 2025349 PMAQI
25th Jul 20253610 PMAQI
25th Jul 20254411 PMAQI
26th Jul 20254612 AMAQI
26th Jul 2025481 AMAQI
26th Jul 2025572 AMAQI
26th Jul 2025563 AMAQI
26th Jul 2025574 AMAQI

25°C23/28°C

26th Jul 2025595 AMAQI
26th Jul 2025606 AMAQI
26th Jul 2025587 AMAQI
26th Jul 2025548 AMAQI
26th Jul 2025619 AMAQI
26th Jul 20255910 AMAQI
26th Jul 20255911 AMAQI
26th Jul 20255412 PMAQI
26th Jul 2025531 PMAQI
26th Jul 2025532 PMAQI
26th Jul 2025523 PMAQI
26th Jul 2025504 PMAQI
26th Jul 2025535 PMAQI
26th Jul 2025546 PMAQI
26th Jul 2025537 PMAQI
26th Jul 2025528 PMAQI
26th Jul 2025539 PMAQI
26th Jul 20255310 PMAQI
26th Jul 20255111 PMAQI
27th Jul 20255112 AMAQI
27th Jul 2025501 AMAQI
27th Jul 2025332 AMAQI
27th Jul 2025283 AMAQI
27th Jul 2025284 AMAQI

25°C21/30°C

27th Jul 2025295 AMAQI
27th Jul 2025306 AMAQI
27th Jul 2025287 AMAQI
27th Jul 2025308 AMAQI
27th Jul 2025309 AMAQI
27th Jul 20252910 AMAQI
27th Jul 20253011 AMAQI
27th Jul 20253412 PMAQI
27th Jul 2025351 PMAQI
27th Jul 2025372 PMAQI
27th Jul 2025393 PMAQI
27th Jul 2025394 PMAQI
27th Jul 2025395 PMAQI
27th Jul 2025426 PMAQI
27th Jul 2025417 PMAQI
27th Jul 2025398 PMAQI
27th Jul 2025369 PMAQI
27th Jul 20253410 PMAQI
27th Jul 20253911 PMAQI
28th Jul 20254012 AMAQI
28th Jul 2025401 AMAQI
28th Jul 2025432 AMAQI
28th Jul 2025453 AMAQI
28th Jul 2025484 AMAQI

27°C23/32°C

28th Jul 2025485 AMAQI
28th Jul 2025526 AMAQI
28th Jul 2025527 AMAQI
28th Jul 2025538 AMAQI
28th Jul 2025559 AMAQI
28th Jul 20255610 AMAQI
28th Jul 20255311 AMAQI
28th Jul 20255312 PMAQI
28th Jul 2025531 PMAQI
28th Jul 2025472 PMAQI
28th Jul 2025513 PMAQI
28th Jul 2025534 PMAQI
28th Jul 2025525 PMAQI
28th Jul 2025536 PMAQI
28th Jul 2025537 PMAQI
28th Jul 2025538 PMAQI
28th Jul 2025529 PMAQI
28th Jul 20255110 PMAQI
28th Jul 20255011 PMAQI
29th Jul 20255112 AMAQI
29th Jul 2025511 AMAQI
29th Jul 2025472 AMAQI
29th Jul 2025503 AMAQI
29th Jul 2025484 AMAQI

26°C19/33°C

29th Jul 2025465 AMAQI
29th Jul 2025466 AMAQI
29th Jul 2025477 AMAQI
29th Jul 2025488 AMAQI
29th Jul 2025499 AMAQI
29th Jul 20255010 AMAQI
29th Jul 20254811 AMAQI
29th Jul 20254612 PMAQI
29th Jul 2025451 PMAQI
29th Jul 2025462 PMAQI
29th Jul 2025453 PMAQI
29th Jul 2025464 PMAQI
29th Jul 2025475 PMAQI
29th Jul 2025466 PMAQI
29th Jul 2025467 PMAQI
29th Jul 2025478 PMAQI
29th Jul 2025499 PMAQI
29th Jul 20254910 PMAQI
29th Jul 20254711 PMAQI
30th Jul 20254712 AMAQI
30th Jul 2025471 AMAQI
30th Jul 2025402 AMAQI
30th Jul 2025403 AMAQI
30th Jul 2025444 AMAQI

26°C21/32°C

30th Jul 2025465 AMAQI
30th Jul 2025436 AMAQI
30th Jul 2025447 AMAQI
30th Jul 2025478 AMAQI
30th Jul 2025489 AMAQI
30th Jul 20254910 AMAQI
30th Jul 20254811 AMAQI
30th Jul 20254912 PMAQI
30th Jul 2025461 PMAQI
30th Jul 2025432 PMAQI
30th Jul 2025463 PMAQI
30th Jul 2025484 PMAQI
30th Jul 2025495 PMAQI
30th Jul 2025496 PMAQI
30th Jul 2025497 PMAQI
30th Jul 2025498 PMAQI
30th Jul 2025499 PMAQI
30th Jul 20254910 PMAQI
30th Jul 20255011 PMAQI
31st Jul 20255012 AMAQI
31st Jul 2025531 AMAQI
31st Jul 2025572 AMAQI
31st Jul 2025603 AMAQI
31st Jul 2025624 AMAQI

25°C21/30°C

31st Jul 2025665 AMAQI
31st Jul 2025686 AMAQI
31st Jul 2025677 AMAQI
31st Jul 2025928 AMAQI
31st Jul 2025869 AMAQI
31st Jul 20257210 AMAQI
31st Jul 20255611 AMAQI
31st Jul 20259612 PMAQI
31st Jul 20251441 PMAQI
31st Jul 20251332 PMAQI
31st Jul 20251033 PMAQI
31st Jul 2025924 PMAQI
31st Jul 2025865 PMAQI
31st Jul 2025806 PMAQI
31st Jul 2025787 PMAQI
31st Jul 2025788 PMAQI
31st Jul 20251129 PMAQI
31st Jul 20259510 PMAQI
31st Jul 20258611 PMAQI
1st Aug 20258412 AMAQI
1st Aug 2025751 AMAQI
1st Aug 2025832 AMAQI
1st Aug 2025743 AMAQI
1st Aug 2025664 AMAQI

21°C17/26°C

1st Aug 2025725 AMAQI
1st Aug 2025646 AMAQI
1st Aug 2025607 AMAQI
1st Aug 2025608 AMAQI
1st Aug 2025589 AMAQI
1st Aug 20255410 AMAQI
1st Aug 20254611 AMAQI
1st Aug 20253612 PMAQI
1st Aug 2025301 PMAQI
1st Aug 2025272 PMAQI
1st Aug 2025263 PMAQI
1st Aug 2025244 PMAQI
1st Aug 2025235 PMAQI
1st Aug 2025206 PMAQI
1st Aug 2025217 PMAQI
1st Aug 2025208 PMAQI
1st Aug 2025439 PMAQI
1st Aug 20252910 PMAQI
1st Aug 20252411 PMAQI
2nd Aug 20253012 AMAQI
2nd Aug 2025361 AMAQI
2nd Aug 2025402 AMAQI
2nd Aug 2025363 AMAQI
2nd Aug 2025294 AMAQI

20°C14/26°C

2nd Aug 2025325 AMAQI
5 AM
2nd Aug 2025316 AMAQI
2nd Aug 2025327 AMAQI
2nd Aug 2025308 AMAQI
2nd Aug 2025319 AMAQI
2nd Aug 20252910 AMAQI
2nd Aug 20253011 AMAQI
2nd Aug 20252812 PMAQI
12 PM
2nd Aug 2025271 PMAQI
8 PM
12 AM
4 AM

--°C/°C

Day time
Avg. Highest Time
5 AM - 8 PM

43AQI

16 hours / Day
480 hours / Month
Avg. Lowest Time
5 AM - 8 PM

43AQI

16 hours / Day
480 hours / Month
In the last 30 days, during the daytime, the highest AQI was between 5 AM to 8 PM (Avg. 43), while the lowest AQI was between 5 AM to 8 PM (Avg. 43).
Night time
Avg. Highest Time
12 AM - 11 PM

43AQI

8 hours / Day
240 hours / Month
Avg. Lowest Time
12 AM - 11 PM

43AQI

8 hours / Day
240 hours / Month
In the last 30 days, during the daytime, the highest AQI was between 12 AM to 11 PM (Avg. 43), while the lowest AQI was between 12 AM to 11 PM (Avg. 43).

2025 Days Vs Air Quality

St Catharines, Ontario, Canada

2025

89%

190

11%

23

Total number of days with different AQI categories in last 214 days in 2025 (151 days remaining)

Good
190 Days
Moderate
23 Days
Poor
0 Days
Unhealthy
0 Days
Severe
0 Days
Hazardous
0 Days

Under WHO’s Safe Air Quality Limits: 89%

Health Risk Level:

Low

In 2025, 89% of 214 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 Catharines, Ontario, Canada

AQI levels in 2025

AQI
PM2.5
PM10
CO
SO2
NO2
O3
Sun.Mon.Tue.Wed.Thu.Fri.Sat.

Jan.

Feb.

Mar.

Apr.

May

Jun.

Jul.

Aug.

Sep.

Oct.

Nov.

Dec.

1st January 2025
25AQI
2nd January 2025
24AQI
3rd January 2025
22AQI
4th January 2025
29AQI
5th January 2025
26AQI
6th January 2025
22AQI
7th January 2025
22AQI
8th January 2025
27AQI
9th January 2025
27AQI
10th January 2025
34AQI
11th January 2025
53AQI
12th January 2025
48AQI
13th January 2025
36AQI
14th January 2025
31AQI
15th January 2025
23AQI
16th January 2025
45AQI
17th January 2025
44AQI
18th January 2025
27AQI
19th January 2025
25AQI
20th January 2025
25AQI
21st January 2025
24AQI
22nd January 2025
28AQI
23rd January 2025
37AQI
24th January 2025
32AQI
25th January 2025
45AQI
26th January 2025
33AQI
27th January 2025
32AQI
28th January 2025
30AQI
29th January 2025
27AQI
30th January 2025
26AQI
31st January 2025
46AQI
1st February 2025
29AQI
2nd February 2025
28AQI
3rd February 2025
54AQI
4th February 2025
25AQI
5th February 2025
23AQI
6th February 2025
32AQI
7th February 2025
28AQI
8th February 2025
35AQI
9th February 2025
29AQI
10th February 2025
30AQI
11th February 2025
46AQI
12th February 2025
29AQI
13th February 2025
34AQI
14th February 2025
30AQI
15th February 2025
34AQI
16th February 2025
33AQI
17th February 2025
28AQI
18th February 2025
27AQI
19th February 2025
22AQI
20th February 2025
21AQI
21st February 2025
26AQI
22nd February 2025
42AQI
23rd February 2025
55AQI
24th February 2025
48AQI
25th February 2025
50AQI
26th February 2025
40AQI
27th February 2025
40AQI
28th February 2025
27AQI
1st March 2025
29AQI
2nd March 2025
27AQI
3rd March 2025
30AQI
4th March 2025
35AQI
5th March 2025
32AQI
6th March 2025
25AQI
7th March 2025
32AQI
8th March 2025
33AQI
9th March 2025
30AQI
10th March 2025
32AQI
11th March 2025
31AQI
12th March 2025
28AQI
13th March 2025
26AQI
14th March 2025
53AQI
15th March 2025
54AQI
16th March 2025
27AQI
17th March 2025
16AQI
18th March 2025
21AQI
19th March 2025
28AQI
20th March 2025
24AQI
21st March 2025
17AQI
22nd March 2025
17AQI
23rd March 2025
19AQI
24th March 2025
21AQI
25th March 2025
20AQI
26th March 2025
19AQI
27th March 2025
21AQI
28th March 2025
26AQI
29th March 2025
25AQI
30th March 2025
28AQI
31st March 2025
22AQI
1st April 2025
16AQI
2nd April 2025
19AQI
3rd April 2025
26AQI
4th April 2025
17AQI
5th April 2025
19AQI
6th April 2025
18AQI
7th April 2025
19AQI
8th April 2025
14AQI
9th April 2025
18AQI
10th April 2025
27AQI
11th April 2025
27AQI
12th April 2025
28AQI
13th April 2025
36AQI
14th April 2025
26AQI
15th April 2025
19AQI
16th April 2025
13AQI
17th April 2025
19AQI
18th April 2025
33AQI
19th April 2025
46AQI
20th April 2025
16AQI
21st April 2025
22AQI
22nd April 2025
16AQI
23rd April 2025
29AQI
24th April 2025
30AQI
25th April 2025
50AQI
26th April 2025
34AQI
27th April 2025
14AQI
28th April 2025
25AQI
29th April 2025
33AQI
30th April 2025
19AQI
1st May 2025
30AQI
2nd May 2025
28AQI
3rd May 2025
17AQI
4th May 2025
17AQI
5th May 2025
18AQI
6th May 2025
19AQI
7th May 2025
28AQI
8th May 2025
17AQI
9th May 2025
22AQI
10th May 2025
24AQI
11th May 2025
21AQI
12th May 2025
27AQI
13th May 2025
32AQI
14th May 2025
19AQI
15th May 2025
27AQI
16th May 2025
27AQI
17th May 2025
28AQI
18th May 2025
17AQI
19th May 2025
17AQI
20th May 2025
14AQI
21st May 2025
15AQI
22nd May 2025
13AQI
23rd May 2025
12AQI
24th May 2025
13AQI
25th May 2025
13AQI
26th May 2025
19AQI
27th May 2025
30AQI
28th May 2025
23AQI
29th May 2025
18AQI
30th May 2025
31AQI
31st May 2025
27AQI
1st June 2025
16AQI
2nd June 2025
20AQI
3rd June 2025
34AQI
4th June 2025
55AQI
5th June 2025
48AQI
6th June 2025
58AQI
7th June 2025
58AQI
8th June 2025
74AQI
9th June 2025
60AQI
10th June 2025
41AQI
11th June 2025
53AQI
12th June 2025
64AQI
13th June 2025
39AQI
14th June 2025
29AQI
15th June 2025
37AQI
16th June 2025
35AQI
17th June 2025
33AQI
18th June 2025
36AQI
19th June 2025
25AQI
20th June 2025
34AQI
21st June 2025
49AQI
22nd June 2025
52AQI
23rd June 2025
53AQI
24th June 2025
55AQI
25th June 2025
44AQI
26th June 2025
38AQI
27th June 2025
35AQI
28th June 2025
30AQI
29th June 2025
36AQI
30th June 2025
42AQI
1st July 2025
36AQI
2nd July 2025
40AQI
3rd July 2025
47AQI
4th July 2025
31AQI
5th July 2025
53AQI
6th July 2025
51AQI
7th July 2025
47AQI
8th July 2025
29AQI
9th July 2025
37AQI
10th July 2025
46AQI
11th July 2025
52AQI
12th July 2025
44AQI
13th July 2025
39AQI
14th July 2025
48AQI
15th July 2025
59AQI
16th July 2025
61AQI
17th July 2025
33AQI
18th July 2025
21AQI
19th July 2025
27AQI
20th July 2025
24AQI
21st July 2025
44AQI
22nd July 2025
30AQI
23rd July 2025
24AQI
24th July 2025
41AQI
25th July 2025
34AQI
26th July 2025
53AQI
27th July 2025
37AQI
28th July 2025
49AQI
29th July 2025
48AQI
30th July 2025
47AQI
31st July 2025
78AQI
1st August 2025
55AQI

31AQI

34AQI

27AQI

24AQI

21AQI

43AQI

42AQI

55AQI

No. of days

Jan.Feb.Mar.Apr.MayJun.Jul.Aug.Sep.Oct.Nov.Dec.Total Days

202532AQI

30
1
26
2
29
2
30
31
20
10
24
7
1
190
23

Highest AQI recorded in

August

55AQI

Lowest AQI recorded in

May

21AQI

202432AQI

30
1
26
3
31
30
31
29
29
2
23
8
28
2
30
1
30
30
1
347
18

Highest AQI recorded in

February

37AQI

Lowest AQI recorded in

November

23AQI

202339AQI

28
3
27
1
30
1
27
3
28
3
11
13
4
2
23
6
2
22
9
29
1
30
1
29
27
3
311
44
6
2

Highest AQI recorded in

June

73AQI

Lowest AQI recorded in

October

26AQI

202231AQI

29
2
22
29
2
17
31
29
1
19
1
1
1
29
30
1
27
3
29
2
292
12
1

Highest AQI recorded in

July

42AQI

Lowest AQI recorded in

August

20AQI

202133AQI

24
6
26
2
28
3
28
2
29
2
30
26
5
31
30
26
5
28
2
30
1
336
28

Highest AQI recorded in

February

38AQI

Lowest AQI recorded in

September

24AQI

202032AQI

13
21
18
30
30
1
31
28
2
29
2
27
3
26
5
253
13

Highest AQI recorded in

June

36AQI

Lowest AQI recorded in

October

28AQI

Most & Least Polluted Years Over the Last 6 Years

Most Polluted Year Recorded
2023(Avg.)
39AQI
Least Polluted Year Recorded
2022(Avg.)
31AQI

St Catharines's annual 2025 AQI (32) shows an average percentage change of -3.9% (improved AQI) compared to previous years: 2020 (32), 2021 (33), 2022 (31), 2023 (39), 2024 (32).