Cornwall weather in December

In December, Cornwall sees average daytime highs of -0°C and overnight lows near -7°C, with 82 mm of precipitation across 12.4 wet days and about 8.6 hours of daylight. It is the 10th-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 2°C in the first days to -2°C by the end. The sky is clear or mostly clear about 9% of the time in December, and the air most often feels dry.

Daylight stretches from about 8 h 48 min at the start of December to 8 h 36 min by month's end. Set against the rest of the year, December is Cornwall's 12th-clearest and 4th-windiest month. For the whole year in context, see Cornwall's year-round climate.

Daytime high
-0°
10th warmest
Overnight low
-7°
3rd coldest
Precipitation
82 mm
12.4 wet days
Daylight
8 h 36 min
7:37 AM – 4:13 PM
Cloud cover
79%
12th clearest
Wind
12 km/h
4th windiest
Solar energy
1.2 kWh/m²
Travel score
0.0
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 December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 2°C in the first days to -2°C by the end.

A typical December day in Cornwall reaches about -0°C in the afternoon and slips back to -7°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between -8°C and 7°C. Set against its neighbours, December runs about 7°C cooler than November and about 4°C warmer than January.

-20°-10°10°151015202531
Avg high (°C)Avg low (°C)
13-4
23-4
32-4
42-5
52-5
61-5
71-5
81-6
91-6
101-6
110-6
120-7
130-7
140-7
150-7
16-1-7
17-1-8
18-1-8
19-1-8
20-1-8
21-1-8
22-1-8
23-1-8
24-1-9
25-2-9
26-2-9
27-2-9
28-2-9
29-2-9
30-2-10
31-2-10

How December really feels in Cornwall

Once humidity and wind are folded in, December averages 0 days that feel above 32°C and 31 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
31
26 feel bitter (≤ -10°C)

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Cornwall weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 9th-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 December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 9% of the time in December, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 10% of December, with mostly cloudy or overcast conditions the remaining 80%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
11882
21981
31882
41882
51882
61882
71882
81882
91882
101981
112080
122080
132080
141981
151981
161981
171981
181981
191981
202080
212080
222080
232080
242080
252179
262179
272179
282179
292080
302080
312080

Chance of precipitation in December

Any precipitationSnow

Cornwall gets around 82 mm of rain and snow over 12.4 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 40% and peaks near 44% on the wettest days, and about 9 days bring snow.

0%10%20%30%40%50%151015202531
Rain chance (%)Snow chance (%)
14423
24324
34324
44225
54225
64126
74127
84027
94028
103929
113929
123930
133930
143931
153931
163931
173931
183931
193931
203931
214031
224032
234032
244032
254032
264032
274032
284033
294033
304033
314134

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in December

Winds average 12 km/h in December.

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

051015151015202531
Wind speed (km/h)Feels
112light breeze
212light breeze
312light breeze
412light breeze
512light breeze
612light breeze
712light breeze
812light breeze
912light breeze
1012calm
1112calm
1212calm
1312calm
1412calm
1512calm
1612calm
1712calm
1812calm
1912calm
2012calm
2112calm
2212light breeze
2312light breeze
2412light breeze
2512light breeze
2612light breeze
2712light breeze
2812light breeze
2912light breeze
3012light breeze
3112light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 8 h 48 min at the start of December to 8 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:24 AM to 7:43 AM, and sunset from 4:14 PM to 4:21 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
18.87:244:14
28.87:254:13
38.87:264:13
48.87:274:13
58.77:284:13
68.77:294:12
78.77:304:12
88.77:314:12
98.77:324:12
108.77:334:12
118.67:334:12
128.67:344:12
138.67:354:12
148.67:364:12
158.67:374:13
168.67:374:13
178.67:384:13
188.67:394:13
198.67:394:14
208.67:404:14
218.67:404:15
228.67:414:15
238.67:414:16
248.67:424:16
258.67:424:17
268.67:424:17
278.67:434:18
288.67:434:19
298.67:434:19
308.67:434:20
318.67:434:21

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.2 kWh/m² — the year's lowest.

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 — December's 1.2 kWh/m² sits near the bottom.

00.511.52151015202531
Solar energy (kWh/m²)Level
11.2Dim
21.2Dim
31.2Dim
41.2Dim
51.2Dim
61.2Dim
71.2Dim
81.2Dim
91.2Dim
101.2Dim
111.2Dim
121.2Dim
131.2Dim
141.2Dim
151.2Dim
161.2Dim
171.2Dim
181.2Dim
191.2Dim
201.2Dim
211.2Dim
221.2Dim
231.2Dim
241.2Dim
251.2Dim
261.2Dim
271.2Dim
281.2Dim
291.3Dim
301.3Dim
311.3Dim
Planning a trip in December

Is December a good time to visit Cornwall?

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

0.0
Sightseeing
10th-best month of the year
0.0
Beach & pool
8th-best month of the year

December is a weaker month for outdoor sightseeing in Cornwall.

What to pack for Cornwall in December

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

In December, Cornwall sees daytime highs around -0°C and nights near -7°C. Pack a warm layer and a heavy coat. Worth having: rain gear. About 12 days see rain.

a warm layera heavy coatrain gear

UV index in Cornwall in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. 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
December 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).