What Is Extreme Cold?
Extreme cold is a period when temperatures become low enough to create significant risks for people, animals and infrastructure. The conditions considered extreme vary depending on the climate of a particular region.
Wind can make extreme cold more dangerous. Even when the actual temperature remains the same, stronger winds increase heat loss from exposed skin and produce lower wind chill values.
Prolonged exposure to extreme cold can increase the risk of frostbite and hypothermia. Very cold weather can also affect vehicles, plumbing, heating systems and other infrastructure.
Related Conditions
| Condition | Description |
| Wind Chill | Describes how cold conditions feel on exposed skin when wind increases heat loss. |
| Cold Wave | A prolonged period of unusually cold weather affecting a region. |
| Temperature Inversion | A layer of warmer air above colder air near the surface, which can trap very cold air in valleys and low-lying areas. |
| Radiational Cooling | Rapid surface cooling that occurs as heat escapes from the ground, especially during clear and calm nights. |
| Polar Vortex | A large circulation of cold air around the polar regions that can influence outbreaks of unusually cold weather. |
Related Alerts
| Alert | Description |
|---|---|
| Extreme Cold Warning | Warns when very cold temperatures or wind chill create dangerous conditions. |
| Wind Warning | Issued when strong winds are expected to reach warning criteria and create hazardous conditions. |
| Blizzard Warning | Warns of strong winds and severely reduced visibility in snow or blowing snow. |
| Winter Storm Warning | Warns of a significant combination of hazardous winter weather. |
| Snow Squall Warning | Warns of snow squalls that can produce sudden poor visibility and hazardous travel. |
What Causes Extreme Cold?
Extreme cold develops when a very cold air mass settles over or moves into a region. These air masses often originate in northern Canada or the Arctic, where limited winter sunlight and snow-covered surfaces allow extremely cold air to develop.
Large-scale atmospheric patterns determine where this cold air travels. During an Arctic outbreak, for example, atmospheric conditions can allow a large mass of cold Arctic air to move south and bring temperatures well below normal.
Clear skies can cause temperatures to fall even further, particularly overnight. Without thick cloud cover, heat from the surface can escape more readily, allowing temperatures near the ground to decrease.
Wind can significantly increase the danger even if it does not lower the actual air temperature. Wind chill describes the additional cooling effect of wind on exposed skin and is an important factor when assessing extreme cold.
Extreme cold can last for a few days or persist much longer when the atmospheric pattern remains in place. Conditions improve when the cold air mass moves away and milder air returns.
FAQ
There is no single temperature that defines extreme cold everywhere. What is considered dangerous depends partly on the climate of the region and the combination of temperature and wind.
A cold snap describes a relatively short period of unusually cold weather. Extreme cold focuses on temperatures becoming sufficiently low to create significant cold-related hazards.
Extreme cold refers to very low-temperature conditions. Wind chill describes how quickly exposed skin loses heat when cold temperatures are combined with wind.
Extreme cold can last from several hours to many days depending on the air mass and atmospheric pattern responsible for the cold weather.
An Extreme Cold Warning is issued when temperatures or wind chill are expected to reach dangerous thresholds. The criteria vary by region because Canadians in different parts of the country are accustomed to different winter climates.