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Cornwall, Ontario climate
Dfa Hot-summer humid continental
Cornwall has a strongly seasonal cool-temperate climate (Hot-summer humid continental, Köppen Dfa). The hottest month is July with an average daily high near 81°F, while the coldest is January averaging around 11°F at night. Precipitation is fairly even year-round, totalling about 39 inches. Snowfall is heavy (78 inches of snow per year on average).
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation split into rain and snow · 1991–2020 normals · hover a month for the exact figuresHours of sunshine per day
Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)Cornwall climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 25 | 28 | 38 | 53 | 68 | 76 | 81 | 79 | 72 | 57 | 44 | 32 |
| Avg temp (°F) | 18 | 20 | 30 | 44 | 58 | 67 | 72 | 70 | 62 | 50 | 38 | 26 |
| Avg low (°F) | 11 | 13 | 23 | 36 | 48 | 57 | 63 | 61 | 53 | 42 | 31 | 20 |
| Precipitation (in) | 3.1 | 2.5 | 2.5 | 3.4 | 3.4 | 3.7 | 3.8 | 3.4 | 3.6 | 4.0 | 3.1 | 3.0 |
| Snowfall (in) | 19.5 | 18.7 | 13.5 | 3.8 | 0.0 | — | — | — | — | 0.3 | 5.8 | 16.8 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°F) | 25 | 28 | 38 | 53 | 68 | 76 |
| Avg temp (°F) | 18 | 20 | 30 | 44 | 58 | 67 |
| Avg low (°F) | 11 | 13 | 23 | 36 | 48 | 57 |
| Precipitation (in) | 3.1 | 2.5 | 2.5 | 3.4 | 3.4 | 3.7 |
| Snowfall (in) | 19.5 | 18.7 | 13.5 | 3.8 | 0.0 | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°F) | 81 | 79 | 72 | 57 | 44 | 32 |
| Avg temp (°F) | 72 | 70 | 62 | 50 | 38 | 26 |
| Avg low (°F) | 63 | 61 | 53 | 42 | 31 | 20 |
| Precipitation (in) | 3.8 | 3.4 | 3.6 | 4.0 | 3.1 | 3.0 |
| Snowfall (in) | — | — | — | 0.3 | 5.8 | 16.8 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 69 | 64 | 63 | 66 | 66 | 63 | 58 | 58 | 58 | 69 | 72 | 73 |
| Relative humidity (%) | 92 | 91 | 85 | 78 | 77 | 79 | 79 | 77 | 76 | 80 | 84 | 90 |
| Wind speed (mph) | 3.0 | 3.6 | 2.9 | 1.8 | 1.0 | 0.9 | 0.9 | 0.9 | 0.9 | 1.0 | 1.1 | 1.8 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 69 | 64 | 63 | 66 | 66 | 63 |
| Relative humidity (%) | 92 | 91 | 85 | 78 | 77 | 79 |
| Wind speed (mph) | 3.0 | 3.6 | 2.9 | 1.8 | 1.0 | 0.9 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 58 | 58 | 58 | 69 | 72 | 73 |
| Relative humidity (%) | 79 | 77 | 76 | 80 | 84 | 90 |
| Wind speed (mph) | 0.9 | 0.9 | 0.9 | 1.0 | 1.1 | 1.8 |
Methodology & sources
Temperature & precipitation — 1991–2020 normals computed from 30 years of daily observations at Cornwall, a weather station, about 2 km from the city centre. The underlying daily records come from NOAA's global station network.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.