Cornwall weather in August

In August, Cornwall sees average daytime highs of 25°C and overnight lows near 15°C, with 94 mm of rain across 11.6 wet days and about 13.9 hours of daylight. It is the 2nd-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 26°C in the first days to 24°C by the end. The sky is clear or mostly clear about 28% of the time in August, and the air most often feels humid.

Daylight stretches from about 14 h 36 min at the start of August to 13 h 12 min by month's end. Set against the rest of the year, August is Cornwall's 2nd-clearest and 12th-windiest month. For the whole year in context, see Cornwall's year-round climate.

Daytime high
25°
2nd warmest
Overnight low
15°
11th coldest
Rainfall
94 mm
11.6 wet days
Daylight
13 h 54 min
5:06 AM – 7:00 PM
Cloud cover
58%
2nd clearest
Wind
10 km/h
12th windiest
Solar energy
5.09 kWh/m²
Travel score
6.6
out of 10

Cornwall is city in Ontario, Canada.

Air quality
Good
PM2.5 6 µg/m³ · 2019
Density
793/km²
people per km²
Founded
1784

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

Temperature in August

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 26°C in the first days to 24°C by the end.

A typical August day in Cornwall reaches about 25°C in the afternoon and slips back to 15°C overnight — a 10°C spread between the day's warmth and the night's chill. On most days the high lands between 21°C and 29°C. Set against its neighbours, August runs about 1°C cooler than July and about 4°C warmer than September.

10°15°20°25°30°151015202531
Avg high (°C)Avg low (°C)
12616
22616
32616
42616
52616
62616
72616
82616
92616
102516
112516
122515
132515
142515
152515
162515
172515
182515
192515
202515
212515
222515
232514
242414
252414
262414
272414
282414
292414
302414
312414

How August really feels in Cornwall

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.

Cornwall weather by month

How August compares with the rest of the year at a glance. August is the 2nd-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-4° / -12°7311.410.590.0
Feb-2° / -12°61108.710.10.0
Mar / -6°7611.2711.60.2
Apr12° / 10112.12.813.22.8
May19° / 9812.20.114.65.6
Jun24° / 13°10512.4015.46.3
Jul26° / 16°10012.9015.16.2
Aug25° / 15°9411.6013.96.6
Sep21° / 11°9310.5012.36.4
Oct13° / 105120.610.73.6
Nov / -1°8412.43.79.30.6
Dec-0° / -7°8212.49.38.60.0

Cloud cover in August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 28% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 23% of August, with mostly cloudy or overcast conditions the remaining 48%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15248
25149
35149
45149
55149
65149
75149
85149
95149
105149
115149
125149
135149
145149
155248
165248
175248
185248
195248
205248
215248
225248
235248
245248
255248
265248
275248
285248
295248
305149
315149

Chance of precipitation in August

Any precipitation

Cornwall gets around 94 mm of rain over 11.6 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 37% and peaks near 41% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202531
Rain chance (%)
141
241
341
441
541
641
741
841
941
1040
1140
1240
1339
1439
1538
1638
1737
1836
1936
2035
2134
2234
2333
2433
2532
2632
2732
2832
2932
3032
3132

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 30% of days. Sticky, muggy-or-worse air turns up on roughly 18% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1162635212
2162734212
3162734212
4172733211
5172733211
6172733211
7182833211
8182832201
9192832201
10192832201
11202832191
12212931191
13212931181
14222931181
15232831171
16242831161
17242831161
18252830151
19262830151
20272830141
21282829141
22302828131
23312728131
24322727131
25332726131
26342725121
27352724121
28362824121
29372823121
30372822111
31382821111

Wind in August

Winds average 10 km/h in August, the calmest month.

Across August, daily wind ranges from about 9 km/h on the calmest days to 10 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
19calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
109calm
119calm
129calm
139calm
149calm
1510calm
1610calm
1710calm
1810calm
1910calm
2010calm
2110calm
2210calm
2310calm
2410calm
2510calm
2610calm
2710calm
2810calm
2910calm
3010calm
3110calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 h 36 min at the start of August to 13 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 84 minutes over August. Sunrise moves from 4:48 AM to 5:24 AM, and sunset from 7:22 PM to 6:34 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.64:487:22
214.54:497:21
314.54:507:19
414.44:517:18
514.44:537:17
614.44:547:15
714.34:557:14
814.34:567:13
914.24:577:11
1014.24:597:10
1114.15:007:08
1214.15:017:07
1314.05:027:05
1414.05:037:03
1514.05:057:02
1613.95:067:00
1713.95:076:59
1813.85:086:57
1913.85:106:55
2013.75:116:53
2113.75:126:52
2213.65:136:50
2313.65:146:48
2413.55:166:46
2513.55:176:45
2613.45:186:43
2713.45:196:41
2813.35:216:39
2913.35:226:37
3013.25:236:36
3113.25:246:34

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 5.09 kWh/m².

For context, solar energy here swings from a low near 1.2 kWh/m² to a high of 5.91 kWh/m² in June across the year — August's 5.09 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.5Bright
45.4Bright
55.4Bright
65.4Bright
75.4Bright
85.3Bright
95.3Bright
105.3Bright
115.2Bright
125.2Bright
135.2Bright
145.2Bright
155.1Bright
165.1Bright
175.1Bright
185.1Bright
195.0Bright
205.0Bright
215.0Bright
224.9Bright
234.9Bright
244.9Bright
254.8Bright
264.8Bright
274.8Bright
284.7Bright
294.7Bright
304.6Bright
314.6Bright
Planning a trip in August

Is August a good time to visit Cornwall?

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

6.6
Sightseeing
1st-best month of the year
5.9
Beach & pool
1st-best month of the year

August is a reasonable time to visit Cornwall for sightseeing.

What to pack for Cornwall in August

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

In August, Cornwall sees daytime highs around 25°C and nights near 15°C. Worth packing: light clothes, rain gear and sun protection. About 12 days see rain.

light clothesrain gearsun protection

UV index in Cornwall in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August peaks around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Cornwall peaks around July 14 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near January 10 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highModerateModerateLowJul 14UV 8Jan 10UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar3Moderate
Apr4Moderate
May6High
Jun6High
Jul8Very high
Aug4Moderate
Sep5High
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Cornwall?

Cornwall sits at 45.0°N, 74.7°W, 59 m above sea level, in Canada. The nearest listed city is Les Coteaux, 49 km away.

Topography around Cornwall

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

Within 3 km, the terrain around Cornwall has only modest variations in elevation — a maximum elevation change of 40 m around an average of 58 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 100 m; within 80 km, large variations in elevation — a maximum elevation change of 1,164 m.

The land around Cornwall is covered by trees (35%) and artificial surfaces (26%) within 3 km, trees (51%) within 16 km, and trees (58%) and cropland (28%) within 80 km.

3 km
40 m
16 km
100 m
80 km
1,164 m
treesgrasslandcroplandartificial surfaceswaterwetland
August weather nearby: Les Coteaux 49 km · Salaberry-de-Valleyfield 53 km · Saint-Lazare 63 km · Vaudreuil-Dorion 69 km · Clarence-Rockland 74 km · Orléans 78 km · Fallingbrook 78 km · Gloucester 80 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 Cornwall (45.0181°, -74.7281°, elevation 59 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. 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).