Photo: Quintin Soloviev · CC BY 4.0

Climate in Cornwall · ECCC 1991–2020 normals

Wet weather: 1,136 mm of rain and snow a year falls on Cornwall, more than on 83% of Canadian towns

On a normal January night the air cools to about −11.5°C. Its July afternoons stay fresher than in 72% of Canadian towns. The year swings widely: the coldest month’s nights and the warmest month’s afternoons are 35°C apart. The furnace earns its keep from October to May, the months that average under 10°C.

July afternoons: cooler than 72% of Canadian towns

January nights: milder than 62% of Canadian towns

Rain and snow a year: wetter than 83% of Canadian towns

Cornwall has no ECCC normals station of its own: every figure here comes from Charlottetown (Airport), 7.9 km north-east.

July high

23.6°C

Typical Canadian town 25.5°C

January low

−11.5°C

Typical Canadian town −13.5°C

Rain & snow a year

1,136 mm

Typical Canadian town 883 mm

Snowfall a year

285 cm

Typical Canadian town 141 cm

Frost days

159

a year at 0°C or below

Frost-free days

153

17 May to 18 Oct

A year in Cornwall at a glance

Each month’s typical high and low, in °C.

Jan−3°C−12°CSnowiest

Feb−3°C−12°CColdest nights

Mar1°C−7°C

Apr7°C−1°C

May14°C4°CLast frost ~17 May

Jun20°C10°C

Jul24°C14°CWarmest

Aug23°C14°C

Sep19°C10°C

Oct13°C5°CWettestFirst frost ~18 Oct

Nov now7°C0°C

Dec1°C−6°C

What stands out about Cornwall’s climate

Compared with Canadian towns, with its place among towns of 2,500+ on Prince Edward Island beside it.

Snowier than 91% of Canadian townsAbout 285 cm of snow falls in a year, most of it in January. 6th snowiest of 12 towns of 2,500+ on Prince Edward Island.Wetter than 83% of Canadian townsAbout 1,136 mm of rain and melted snow a year; October is the wettest month and April the driest. 6th wettest of 12 towns of 2,500+ on Prince Edward Island.A narrower year than 78% of Canadian townsFrom January nights to July afternoons, the year spans 35.1°C.

A normal year

What a year in Cornwall feels like

Typical highs and lows by season and by month, from ECCC’s 1991–2020 normals.

Winter

−2°C / −10°C

302 mm, with 197 cm of snow

Spring

8°C / −1°C

237 mm, with 66 cm of snow

Summer

22°C / 13°C

269 mm of rain and snow

Autumn

13°C / 5°C

327 mm, with 22 cm of snow: the wettest season

−20°

−15°

−10°

−5°

0°

5°

10°

15°

20°

25°

30°

−3°C−12°C

1°C−7°C

7°C−1°C

14°C4°C

20°C10°C

24°C14°C

23°C14°C

19°C10°C

13°C5°C

7°C0°C

1°C−6°C

JanFebMarAprMayJunJulAugSepOctNovDec

Best months to be outsideJunJulAugSepHighs of 17–27°C and nights of 8°C or more

Frost & warm days

About 159 frosts and 83 warm days a year

From October to May frost is routine, and in January it comes on almost every night. On about 6 nights a year the air falls below −20°C.

153 frost-free days · average dates, 1991–2020

17 May 18 Oct

JanFebMarAprMayJunJulAugSepOctNovDec

159

Frost days a year (0°C or below)

Fewer frosts than 50% of Canadian towns

Days that stay below 0°C

Nights a year below −20°C

Days a year above 20°C

Days a year above 30°C

Frost days by month

Average days at 0°C or below

JFMAMJJASOND

Days above 20°C by month

Average days

JFMAMJJASOND

Rain & snow

1,136 mm of precipitation in a typical year

October is the wettest month and April the driest. 6th wettest of 12 towns of 2,500+ on Prince Edward Island. Some 135 days a year see 1 mm of rain or snow or more.

1,136 mm

Rain and snow a year

Wetter than 83% of Canadian towns

872 mm

Of it as rain alone (77%)

122 mm

October, the wettest month

75 mm

April, the driest month

Rain and snow by month

Millimetres

122 mm

JFMAMJJASOND

Rain alone by month

Millimetres

120 mm

JFMAMJJASOND

Snow

285 cm of snow in a typical year

From October to May snow is likely; January is the peak, at about 73 cm. 6th snowiest of 12 towns of 2,500+ on Prince Edward Island.

285 cm

Snowfall a year

Snowier than 91% of Canadian towns

Days a year with 0.2 cm of snow or more

113

Days a year with 1 cm or more on the ground

32 cm

Snow on the ground at the end of February, the deepest month

Snowfall by month

Centimetres

73 cm

JFMAMJJASOND

Snow on the ground by month

Centimetres at month’s end

32 cm

JFMAMJJASOND

Heating

Heating a home in Cornwall

88% of a year’s heating need falls between October and April. Months averaging under 10°C: October to May.

4,517 heating degree days (below 18°C)a year, 1991–2020

1,739 growing degree days (above 5°C)a year, 1991–2020

Behind the figure: the degrees each day’s mean falls under 18°C, summed for the year.

Living here

Living with Cornwall’s climate

The averages read for the garden, the outdoors and the coldest and hottest days.

The garden window

A normal year gives the garden about 153 frost-free days, roughly 17 May to 18 October.

Get outside

Warm afternoons without cold nights, 17–27°C and 8°C or more, mark Jun, Jul, Aug and Sep.

Parks & trails →

Wind chill

Winter brings about 29 days with a wind chill below −20.

Humidex

Muggy heat with a humidex over 30 arrives on about 25 days a year.

Storms and extremes

A normal year has no blizzard, flood or heat wave in it; Cornwall’s hazards page looks at those.

Flood & hazards →

Weather station

ECCC’s normals location: Charlottetown (Airport)

Behind the 1991–2020 normals for Charlottetown (Airport) are 2 stations, which ECCC combines into one record.

Distance from the town	7.9 km north-east
Station altitude	49 m
Completeness	at least 20 years
WMO standard normals	No
Coldest reading, 1991–2020	−29.8°C
Hottest reading, 1991–2020	33.0°C
Average wind	16.4 km/h on average, most often from the west
Next-nearest location	Elmwood, 10 km

Compared with other towns

How Cornwall compares

Against the 2,611 Canadian towns and neighbourhoods of 2,500 or more, each read from its own normals location; the dots are the other locations those towns use on Prince Edward Island.

July afternoons23.6°C

CornwallMedian Canadian town

20°C22°C24°C26°C28°C

Cooler than 72% of Canadian towns7th warmest of 12 towns of 2,500+ on Prince Edward Island

January nights−11.5°C

CornwallMedian Canadian town

−20°C−15°C−10°C−5°C0°C

Milder than 62% of Canadian towns7th mildest of 12 towns of 2,500+ on Prince Edward Island

Rain and snow a year1,136 mm

CornwallMedian Canadian town

05001,0001,5002,000

Wetter than 83% of Canadian towns6th wettest of 12 towns of 2,500+ on Prince Edward Island

Snowfall a year285 cm

CornwallMedian Canadian town

100200300400

Snowier than 91% of Canadian towns6th snowiest of 12 towns of 2,500+ on Prince Edward Island

Next door

Nearby towns’ climate

Places around Cornwall whose figures come from another normals location.

Town	July high	January low	Rain & snow
Cornwall Charlottetown (Airport)	23.6°C	−11.5°C	1,136 mm
Charlottetown 5.4 km · Charlottetown (Airport)	23.6°C about the same	−11.5°C about the same	1,136 mm
Kingston 8.8 km · Elmwood	23.7°C about the same	−11.0°C 0.5°C milder	1,290 mm

Month by month

Cornwall weather by month

Average daily high and low, mean temperature, rain and snow (as water) and snowfall by month, 1991–2020.

Month	High	Low	Mean	Rain & snow	Snow
January	−3.0°C	−11.5°C	−7.3°C	101 mm	73 cm
February	−2.9°C	−11.6°C	−7.3°C	85 mm	62 cm
March	1.4°C	−6.5°C	−2.6°C	84 mm	42 cm
April	7.3°C	−1.4°C	3.0°C	75 mm	21 cm
May	14.2°C	3.9°C	9.1°C	78 mm	2 cm
June	19.5°C	9.6°C	14.6°C	91 mm	0 cm
July	23.6°C	14.4°C	19.0°C	82 mm	0 cm
August	23.3°C	14.1°C	18.8°C	96 mm	0 cm
September	19.1°C	10.0°C	14.6°C	95 mm	0 cm
October	12.6°C	4.6°C	8.6°C	122 mm	2 cm
November	6.7°C	−0.2°C	3.2°C	110 mm	21 cm
December	0.9°C	−6.3°C	−2.7°C	115 mm	63 cm
Year	10.2°C	1.6°C	5.9°C	1,136 mm	285 cm

Year to year

In March, anything from −23.3°C to 24.5°C

Bars run from each month’s record low to its record high over 1991–2020; January is the month whose average wanders most from year to year (±2.4°C around −7.3°C), August the one that wanders least (±1.0°C).

−40°

−30°

−20°

−10°

0°

10°

20°

30°

40°

JanFebMarAprMayJunJulAugSepOctNovDec

Record low to record high, 1991–2020Normal

Sources

Where Cornwall’s numbers come from

Averages over 30 years, not a forecast.

Normals: Environment and Climate Change Canada’s 1991–2020 normals, Charlottetown (Airport): the nearest of its locations with every month’s temperatures.
Comparisons: the 2,500-plus towns and neighbourhoods of Canada, each read from its closest normals location; whole cities and reserves aren’t counted.
Not on this page: sunshine (no 1991–2020 normals exist for it) and any altitude adjustment, since there is no elevation for the town itself.

Canadian Climate Normals 1991–2020 · ECCC Data Services End-use Licence. Data Source: Environment and Climate Change Canada

Questions about Cornwall’s climate

How warm does Cornwall get in summer?

Midsummer means July, with afternoons near 23.6°C on a typical day.

How cold does Cornwall get in winter?

On a normal February night the air drops to −11.6°C, the coldest of the year.

How much rain and snow does Cornwall get?

Precipitation totals 1,136 mm a year, with October the wettest month (122 mm) and April the driest (75 mm).

How long does snow stay on the ground?

The ground is white, with 1 cm or more, on some 113 days a year.

Are these figures for Cornwall itself?

No: Cornwall has no normals location, so the figures come from Charlottetown (Airport), the nearest with 1991–2020 normals.

Data Source: Environment and Climate Change Canada · ECCC Data Services End-use Licence Today’s forecast for Cornwall →

Adapted from Statistics Canada (Census of Population 2021, population estimates 2025, 2021 census boundaries) under the Statistics Canada Open Licence; this does not constitute an endorsement by Statistics Canada. Neighbourhood names in some cities © OpenStreetMap contributors (ODbL).