St. Catharines weather in August

In August, St. Catharines sees average daytime highs of 24°C and overnight lows near 19°C, with 75 mm of rain across 9.9 wet days and about 13.8 hours of daylight. It is the 2nd-warmest and 10th-wettest month of the year here.

Day-to-day highs hold fairly steady near 24°C through the month. The sky is clear or mostly clear about 39% of the time in August, and the air most often feels humid.

Daylight stretches from about 14 h 24 min at the start of August to 13 h 06 min by month's end. Set against the rest of the year, August is St. Catharines's 1st-clearest and 11th-windiest month. For the whole year in context, see St. Catharines's year-round climate.

Daytime high
24°
2nd warmest
Overnight low
19°
11th coldest
Rainfall
75 mm
9.9 wet days
Daylight
13 h 48 min
5:28 AM – 7:15 PM
Cloud cover
52%
1st clearest
Wind
12 km/h
11th windiest
Solar energy
5.34 kWh/m²
Travel score
7.1
out of 10

St. Catharines is city in Ontario, Canada.

Air quality
Good
PM2.5 7 µg/m³ · 2019
Density
1,410/km²
people per km²
Founded
1783

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 24°C through the month.

A typical August day in St. Catharines reaches about 24°C in the afternoon and slips back to 19°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 21°C and 27°C. Set against its neighbours, August runs on par with July and about 4°C warmer than September.

10°15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
12520
22520
32520
42520
52520
62520
72520
82520
92520
102520
112520
122520
132519
142419
152419
162419
172419
182419
192419
202419
212419
222419
232419
242419
252419
262419
272419
282419
292418
302318
312318

How August really feels in St. Catharines

Once humidity and wind are folded in, August averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

August sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

St. Catharines weather by month

How August compares with the rest of the year at a glance. August is the 2nd-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-0° / -5°7511.999.20.0
Feb-0° / -6°599710.20.0
Mar / -2°7310.44.611.60.1
Apr / 9711.71.813.11.8
May15° / 10°8311.4014.44.5
Jun21° / 16°9111.1015.16.4
Jul25° / 20°8810.8014.96.9
Aug24° / 19°759.9013.87.1
Sep21° / 16°859.8012.36.5
Oct14° / 9212.10.110.84.1
Nov / 8210.829.51.3
Dec / -1°7711.66.68.90.0

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 39% of the time in August, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 23% of August, with mostly cloudy or overcast conditions the remaining 39%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16040
26139
36139
46238
56238
66139
76238
86238
96337
106337
116337
126337
136337
146337
156337
166337
176238
186238
196238
206238
216139
226139
236139
246040
256040
266040
275941
285941
295941
305842
315842

Chance of precipitation in August

Any precipitation

St. Catharines gets around 75 mm of rain over 9.9 wet days in August. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 32% and peaks near 36% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202531
Rain chance (%)
136
236
335
435
535
635
735
835
934
1034
1134
1234
1334
1433
1533
1633
1733
1832
1932
2031
2131
2230
2330
2429
2529
2629
2729
2829
2929
3029
3129

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

Most of August feels humid — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, August lands in the humid band about 31% of days. Sticky, muggy-or-worse air turns up on roughly 35% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
181833329
281933329
381932319
481932319
582032319
682032309
792031309
892131309
992131309
10102131299
11102131299
12112231298
13112231298
14112231288
15112231287
16122231287
17122232287
18122232286
19132232276
20132232276
21132232276
22142232266
23142232266
24152332255
25152332255
26152431245
27162431245
28162530245
29172530235
30182529235
31182629225

Wind in August

Winds average 12 km/h in August.

Across August, daily wind ranges from about 12 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
112calm
212calm
312calm
412calm
512calm
612calm
712calm
812calm
912calm
1012calm
1112calm
1212calm
1312calm
1412calm
1512calm
1612light breeze
1712light breeze
1812light breeze
1912light breeze
2012light breeze
2112light breeze
2212light breeze
2312light breeze
2413light breeze
2513light breeze
2613light breeze
2713light breeze
2813light breeze
2913light breeze
3013light breeze
3113light breeze

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 h 24 min at the start of August to 13 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over August. Sunrise moves from 5:11 AM to 5:44 AM, and sunset from 7:35 PM to 6:50 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.45:117:35
214.45:127:34
314.35:137:33
414.35:147:31
514.25:157:30
614.25:167:29
714.25:187:28
814.15:197:26
914.15:207:25
1014.05:217:23
1114.05:227:22
1214.05:237:21
1313.95:247:19
1413.95:257:18
1513.85:267:16
1613.85:287:15
1713.75:297:13
1813.75:307:11
1913.65:317:10
2013.65:327:08
2113.65:337:07
2213.55:347:05
2313.55:357:03
2413.45:377:02
2513.45:387:00
2613.35:396:58
2713.35:406:57
2813.25:416:55
2913.25:426:53
3013.15:436:51
3113.15:446:50

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 5.34 kWh/m².

For context, solar energy here swings from a low near 1.28 kWh/m² to a high of 6.32 kWh/m² in June across the year — August's 5.34 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.8Bright
25.8Bright
35.7Bright
45.7Bright
55.7Bright
65.6Bright
75.6Bright
85.6Bright
95.5Bright
105.5Bright
115.5Bright
125.4Bright
135.4Bright
145.4Bright
155.3Bright
165.3Bright
175.3Bright
185.3Bright
195.2Bright
205.2Bright
215.2Bright
225.1Bright
235.1Bright
245.1Bright
255.0Bright
265.0Bright
275.0Bright
284.9Bright
294.9Bright
304.8Bright
314.8Bright
Planning a trip in August

Is August a good time to visit St. Catharines?

Our two travel scores rate August for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

7.1
Sightseeing
1st-best month of the year
6.1
Beach & pool
1st-best month of the year

August is one of the better times to visit St. Catharines for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for St. Catharines in August

From August's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In August, St. Catharines sees daytime highs around 24°C and nights near 19°C. Worth packing: light clothes, rain gear and sun protection. About 10 days see rain.

light clothesrain gearsun protection

Sea temperature near St. Catharines in August

The nearest coast averages about 22°C in August — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 25 km away) is warmest in August at about 22°C and coldest in February near 3°C.

It's comfortable for a long swim from Jul 17 to Sep 6 — about 1.7 months when the water holds above 20°C.

0°10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan4Bracing
Feb3Bracing
Mar3Bracing
Apr4Bracing
May7Bracing
Jun15Bracing
Jul20Refreshing
Aug22Refreshing
Sep19Cool
Oct13Bracing
Nov8Bracing
Dec5Bracing

UV index in St. Catharines in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in St. Catharines peaks around June 19 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 21 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 19UV 8Dec 21UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr5High
May6High
Jun8Very high
Jul7Very high
Aug6High
Sep5High
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is St. Catharines?

St. Catharines sits at 43.2°N, 79.2°W, 102 m above sea level, in Canada. The nearest listed city is Thorold, 7.0 km away.

Topography around St. Catharines

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of St. Catharines.

Within 3 km, the terrain around St. Catharines has only modest variations in elevation — a maximum elevation change of 47 m around an average of 100 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 193 m; within 80 km, significant variations in elevation — a maximum elevation change of 483 m.

The land around St. Catharines is covered by artificial surfaces (51%) and trees (33%) within 3 km, water (33%) and trees (20%) within 16 km, and water (41%) and trees (24%) within 80 km.

3 km
47 m
16 km
193 m
80 km
483 m
treesgrasslandcroplandartificial surfaceswater
August weather nearby: Thorold 7.0 km · Niagara-on-the-Lake 16 km · Niagara Falls 16 km · Niagara Falls 17 km · Welland 21 km · Grimsby 26 km · Grand Island 27 km · Port Colborne 30 km

Canada travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 83% of US
price level, 2025
GDP per capita
$55,698
2025
Happiness
6.7 / 10
World Happiness, 2025
Safe drinking water
97%
of population, 2024
Homicide rate
2
per 100k, 2023
Road deaths
5.3
per 100k/yr, 2019
Income group
High
World Bank
Religion
Christian 53%none 35%Muslim 5%Hindu 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for St. Catharines (43.1713°, -79.2427°, elevation 102 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).