Environment and Climate Change Canada issues Winter weather and cold alerts across Canada. In Southern Ontario, extreme cold warnings are issued by Environment Canada when the temperature or wind chill is expected to reach minus 30°C for at least two hours.
Extreme cold warnings are issued when very cold temperatures or wind chill creates an increased risk to health, such as frostbite and hypothermia. Risks are greater for young children, older adults, people with chronic illnesses, people working or exercising outdoors, and those without proper shelter and clothing.