What Is an Extreme Cold Warning?
An Extreme Cold Warning alerts the public when extremely cold temperatures or very low wind chill values are expected to create hazardous conditions.
Extreme cold can cause the body to lose heat rapidly and increases the risk of frostbite and hypothermia. Strong winds can make conditions feel considerably colder by increasing heat loss from exposed skin.
The severity of extreme cold varies across Canada. A temperature considered unusually cold in southern Ontario may be relatively common in parts of northern Canada, so cold-warning criteria vary depending on location.
Related Warnings
| Warning or Alert | Description |
|---|---|
| Winter Storm Warning | Issued when multiple types of severe winter weather are expected together and may produce significant impacts. |
| Winter Storm Watch | Issued when conditions are favourable for a significant winter storm to develop, but its exact timing, location or severity remains uncertain. |
| Blizzard Warning | Issued when strong winds and snow or blowing snow create widespread severely reduced visibility. |
When Is an Extreme Cold Warning Issued?
An Extreme Cold Warning is issued when significant cold temperatures or very low wind chill values are expected to create hazardous conditions.
There is no single temperature or wind chill threshold that applies everywhere in Canada. The conditions required for a warning vary geographically because normal winter temperatures differ substantially between southern, northern, coastal and inland regions.
Wind chill is particularly important because it describes how cold the combination of air temperature and wind feels on exposed skin. Environment and Climate Change Canada includes wind chill in forecasts when temperatures are below 0°C and wind speeds reach at least 5 km/h.
Under Canada’s current impact-based warning system, the warning colour can also vary according to the expected impacts and forecast confidence. A yellow warning generally represents moderate impacts, an orange warning represents higher-impact conditions, and a red warning is reserved for extreme impacts.
What Weather Conditions Should You Expect?
During an Extreme Cold Warning, expect very low temperatures, dangerously low wind chill values, or both.
Strong winds can increase heat loss and make exposed skin freeze much faster than the air temperature alone would suggest.
Environment and Climate Change Canada’s Wind Chill Index classifies:
- -10 to -27: Moderate risk
- -28 to -39: High risk
- -40 to -47: Very high risk
- -48 to -54: Severe risk
- -55 or colder: Extreme risk
At wind chill values between -28 and -39, exposed skin can freeze in approximately 10 to 30 minutes. At -40 to -47, exposed skin can freeze in approximately 5 to 10 minutes, while at -55 or colder, it can freeze in less than two minutes.
Extreme cold can occur during an Arctic outbreak, cold wave or cold snap when very cold air spreads across a region. Snow does not need to be falling for extreme cold conditions to become dangerous.
What Should You Do During an Extreme Cold Warning?
Limit unnecessary exposure to the cold and pay close attention to wind chill values before spending extended periods outdoors.
During an Extreme Cold Warning:
- Wear several layers of warm clothing.
- Cover exposed skin, including your hands, face, ears and neck.
- Wear insulated and wind-resistant outer layers.
- Limit time outdoors when wind chill values become dangerous.
- Take regular warming breaks if you must remain outside.
- Watch for signs of frostbite and hypothermia.
- Check on people who may be particularly vulnerable to extreme cold.
- Keep pets indoors or limit their time outside during severe cold.
- Monitor current forecasts and weather warnings for changing conditions.
If travelling, prepare for the possibility of vehicle problems during extreme cold. Very low temperatures can affect batteries, tire performance and other vehicle systems.
FAQ
An Extreme Cold Warning means extremely cold temperatures or very low wind chill values are expected to create conditions that can threaten health and safety.
There is no single Canada-wide temperature threshold. Cold-warning criteria vary by location because what qualifies as unusually dangerous cold differs considerably across Canada’s climate regions.
The risk becomes high at a wind chill of -28 to -39, when exposed skin can freeze in approximately 10 to 30 minutes. At lower wind chill values, frostbite can develop much faster.
An Extreme Cold Warning focuses on hazards from very low temperatures or wind chill. A Winter Storm Warning is used when multiple types of severe winter weather are expected together.
