Cornwall climate — normals and trends
Cornwall (Canada) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 7.0 °C and it receives 1,059 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (20.8 °C on average) and the coldest is January (-8.5 °C). Rainfall peaks in July.
Cornwall averages 142 frost days, 10 hot days (≥ 30 °C) and 147 rainy days per year.
Cornwall has warmed by +1.5 °C between 1940 and 2025, or +0.18 °C per decade. This trend is statistically significant.
The number of frost days there went from about 150 to 134 per year over the period.
The hottest day of the period reached 36.8 °C (on 4 August 1955) and the coldest -36.5 °C (on 15 January 1957).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
CornwallOntario
- coords
- 45.02°, -74.73°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
7.0°C
Average daily high
11.7°C
Average daily low
2.3°C
Annual rainfall
1,059mm
Sunshine / day
8.3h
Mean relative humidity
73%
Average peak wind
16.3km/h
Seasonal range
29.3°C
Frost days (< 0 °C)
142 d/yr
Hot days (≥ 30 °C)
10 d/yr
Rainy days (≥ 1 mm)
147 d/yr
Annual snowfall
147.8 cm
Average feels-like high
9.4 °C
Average feels-like low
-0.8 °C
Average peak gust
37.3 km/h
Tropical nights (≥ 20 °C)
7 d/yr
Solar radiation
13.3 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.5 °C
since 1940
+0.2 °C per decade · r² = 0.28 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
36.8 °C
4 August 1955
Coldest day
-36.5 °C
15 January 1957
Wettest day
102 mm
31 August 2005
Windiest day
45.0 km/h
14 January 1950
Strongest gust
109.4 km/h
13 November 1992
Hottest feels-like
41.5 °C
1 July 2018
Coldest feels-like
-41.6 °C
15 January 1957
Snowiest day
29.2 cm
3 April 1975
Sunniest day
15.4 h
22 June 2023
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | -4.4 °C | -0.2 °C | 52 mm | -16 mm |
| Feb | -3.9 °C | -1.3 °C | 90 mm | +23 mm |
| Mar | 5.9 °C | +2.7 °C | 97 mm | +20 mm |
| Apr | 12.4 °C | +1.0 °C | 108 mm | +13 mm |
| May | 18.8 °C | 0.0 °C | 94 mm | +1 mm |
| Jun | 25.5 °C | +1.9 °C | 63 mm | -35 mm |
| Jul | 28.1 °C | +2.2 °C | 88 mm | -13 mm |
| Aug | 26.6 °C | +1.9 °C | 51 mm | -48 mm |
| Sep | 23.0 °C | +2.6 °C | 60 mm | -33 mm |
| Oct | 16.1 °C | +2.5 °C | 175 mm | +79 mm |
| Nov | 4.0 °C | -2.1 °C | 100 mm | +11 mm |
| Dec | -2.3 °C | -1.3 °C | 84 mm | -1 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Cornwall?
Cornwall has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 7.0 °C and it receives 1,059 mm of precipitation per year.
What is the hottest day ever recorded in Cornwall?
The hottest day measured in Cornwall between 1940 and 2025 was 4 August 1955, reaching 36.8 °C.
What is the coldest day in Cornwall?
The coldest day measured in Cornwall between 1940 and 2025 was 15 January 1957, at -36.5 °C.
Does it snow in Cornwall?
Yes. Cornwall gets on average 147.8 cm of snow per year and has around 142 frost days.
Has the climate of Cornwall warmed?
Yes: Cornwall warmed by +1.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Cornwall?
The wettest day measured in Cornwall between 1940 and 2025 was 31 August 2005, with 102 mm of rain in 24 hours.
What was the windiest day in Cornwall?
The windiest day measured in Cornwall between 1940 and 2025 was 14 January 1950, with winds reaching 45.0 km/h.
What is the warmest month in Cornwall?
The warmest month in Cornwall is July (20.8 °C on average); the coldest is January (-8.5 °C).
How much does it rain in Cornwall?
Cornwall receives on average 1,059 mm of precipitation per year, spread over about 147 rainy days.
Is it sunny in Cornwall?
Cornwall gets on average 8.3 hours of sunshine per day, roughly 3,030 hours per year over 1940-2025.
What is the biggest single-day snowfall in Cornwall?
The heaviest 24-hour snowfall measured in Cornwall between 1940 and 2025 was 3 April 1975, with 29.2 cm.
Are there tropical nights in Cornwall?
Yes: Cornwall has on average 7 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Cornwall?
In Cornwall, between 1940 and 2025, the highest apparent temperature reached 41.5 °C on 1 July 2018, and the lowest was -41.6 °C on 15 January 1957.
Compare Cornwall with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Cornwall