While waiting at a bus stop, or simply walking outside on a cold winter’s day, you may notice how much colder you feel when the wind is blowing. Wind actually speeds up the rate at which your body loses heat.
The wind chill index was developed to help Canadians avoid the health hazards of cold windy days. Wind chill describes how cold you feel on a winter day by combining the cooling effects of both low temperature and wind. The index is expressed in temperature-like units, which makes it easy to understand and use. Having a wind chill index of -25 on a day when the outdoor temperature is -15 C means that, given the wind, it will feel like a -25 C calm wind-free day.
Serious health problems can arise from exposure to extreme cold. Every year, more than 80 Canadians die from being out in the cold too long. Many more suffer injuries such as hypothermia and frostbite, which are related to cold. These injuries are more common on windy days, as wind increases your loss of body heat. The wind chill index considers the cooling effects of both temperature and wind. It is a better measure of the discomfort you feel on a cold day than temperature alone. Thanks to this, it is a simple, practical tool that you can use to protect yourself and your family on cold winter days.
Range of Wind Chill
Risk of frostbite
What to do
|0 to -9||Low||Slight increase in discomfort.||Dress warmly.|
|-10 to -27||Low||Uncomfortable.||Hypothermia if outside for long periods of time. Dress in layers
of warm clothing.
|-28 to -39||Increasing risk: exposed skin can freeze in 10 to 30 minutes.||Check face and extremities for numbness and whiteness. Risk of hypothermia if outside for long periods.||Cover exposed skin. Wear a hat, mittens, scarf or face mask. Stay active.|
|-40 to -47||High risk: exposed skin can freeze in five to 10 minutes.||Check face and extremities frequently. Risk of hypothermia if outside for long periods.||Cover all exposed skin. Wear a hat, mittens, scarf or face mask. Stay active.|
|-48 to -54||High risk: exposed skin can freeze in two to five minutes.||Check face and extremities frequently. Serious risk of hypothermia if outside for long periods.||Be careful. Cover all exposed skin. Be ready to cut short or cancel outdoor activities.|
|-55 and colder||High risk: exposed skin can freeze in less than two minutes.||Danger! Outdoor conditions
We all run the risk of suffering cold-related injuries if we stay outside too long on a cold windy day. However, some are at more risk. Elderly people and children are particularly vulnerable since they have less muscle mass. They create less protective body heat. Similarly, people with tall slim builds feel the cold more quickly. Their body type makes them lose heat faster than those who are shorter and heavier.
Environment Canada Inquiry Centre
351 St. Joseph Boulevard
Place Vincent Massey, 8th floor
(in Canada only)
or (819) 997-2800
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Wind chill site:
In addition to age and physical condition, other factors influence how much heat you lose on a cold day. Good quality clothing with insulating properties keeps in heat and protects you from cold. Wet clothing, on the other hand, loses its insulating value and chills your body rapidly.
On cold days, you should be aware of the wind chill index in the weather forecast from Environment Canada or your local weather forecast sources. Use this wind chill information to decide how to dress before going outside, and to consider your family’s outdoor activities. Many Canadian schools use wind chill values to decide whether it is safe for children to go outdoors at recess. Sports groups, such as hockey clubs, also use the system to decide whether or not to cancel outdoor practices on a cold winter day.
Outdoor physical activity is important for you and your family’s health. When you choose to go outside when it is cold, remember to protect yourself by following these tips.