What is the climate like in Canada's prairies?

The Canadian Prairies have a humid continental climate dominated by long cold winters, warm to hot summers, modest precipitation, and significant temperature extremes between seasons. The region covers most of Alberta, Saskatchewan, and Manitoba, with the Prairie ecozone extending from the Rocky Mountain foothills in the west to the western edge of the Canadian Shield in southeastern Manitoba. The flat to gently rolling terrain, low humidity, and relatively dry air create some of the most distinctive weather patterns in North America.

Winters are long and cold across the prairies. Mean January temperatures range from minus 11 degrees Celsius in Calgary (the warmest major prairie city, due to chinook winds from the Rockies) to minus 16 degrees Celsius in Saskatoon and minus 18 degrees Celsius in Winnipeg. Extreme cold of minus 40 degrees Celsius and below occurs every winter and can persist for several consecutive days, particularly in Manitoba and central Saskatchewan where the Arctic air is unobstructed by mountain ranges. Snowfall is moderate (about 100 to 130 centimetres annually) and tends to remain on the ground from November to April.

Summers are warm to hot and notably sunny. Mean July temperatures range from 17 to 19 degrees Celsius, and daytime highs frequently reach 28 to 32 degrees Celsius across the southern prairies. Summer precipitation comes primarily as thunderstorms, sometimes producing severe weather including supercell storms, large hail, and tornadoes. The southern prairies are part of Tornado Alley North; Canada's worst tornado disaster (the Edmonton Tornado of July 31, 1987) killed 27 people, and the Pine Lake Tornado in Alberta (July 14, 2000) killed 12 people.

The Chinook winds are a distinctive prairie weather phenomenon. Warm dry air descending the eastern slopes of the Rockies can raise winter temperatures by 20 to 30 degrees Celsius within hours, melting snow and producing the characteristic 'Chinook arch' cloud over Calgary, Lethbridge, and southern Alberta. The Palliser Triangle, a semi-arid region of southern Alberta and Saskatchewan named after British explorer Captain John Palliser (who surveyed it 1857 to 1860), has the lowest precipitation in agricultural Canada at about 350 millimetres per year and was the heart of the Dust Bowl drought of the 1930s. Climate change is reshaping prairie weather, with wildfires (Fort McMurray 2016, Lytton 2021), drought, and heat waves all becoming more severe.