Wind Chill Calculator: Your Guide to Cold Weather Safety
The weather outside feels colder when it is windy, and we call this the wind chill. Environment Canada uses wind chill in weather forecasts to show how cold it will feel outside, helping Canadians make informed decisions to stay safe during winter. The Wind Chill Calculator helps you understand the perceived temperature on your skin, combining actual air temperature with wind speed to give you a "feels like" value.
On cold days with no wind, your body creates a thin layer of warm air around your skin. When the wind blows, this protective layer is stripped away, drying moisture off your skin and making you feel colder. As this layer evaporates, you lose heat faster, and your body must work harder to warm up a new layer of air. If your skin is wet, it gets cold even quicker because there is more moisture to evaporate.
How Wind Chill Affects Your Body
Wind chill cannot be measured with a thermometer—it is felt by our skin. Environment Canada uses the Wind Chill Index to calculate the feeling of cold from wind when temperatures are below zero. This index helps describe the risk of frostbite and shows how cold really feels, so you can take action to stay safe.
For example, if the outside temperature is -10°C but the wind chill is -20, when you are in the wind it will feel like -20°C on your skin. However, it's important to understand that wind chill does not make objects colder than the actual air temperature. If the air temperature is -20°C and the wind chill is -30, objects outside will only cool to -20°C, not -30°C.
Wind Chill Safety Risk Levels (Environment Canada)
How Wind Chill is Calculated
Environment Canada uses a standardized formula to calculate wind chill. When air temperature is ≤ 0°C and reported wind speed is ≥ 5 km/h, the following equation is used:
Where T is the air temperature in °C and V is the wind speed at 10 meters (standard anemometer height) in km/h.
When wind speed is between 0 and 5 km/h, a different formula is applied:
Wind Chill Reference Table
| Wind Speed | Estimating Wind Speed | -10°C | -20°C | -30°C | -40°C |
|---|---|---|---|---|---|
| 10 km/h | Wind felt on face | -15 | -27 | -39 | -51 |
| 20 km/h | Small flags extended | -18 | -30 | -43 | -56 |
| 30 km/h | Small branches move | -20 | -33 | -45 | -59 |
| 40 km/h | Small trees sway | -21 | -34 | -48 | -61 |
| 50 km/h | Large branches move | -22 | -35 | -49 | -63 |
How to Estimate Wind Chill Without a Calculator
You can estimate wind chill by observing the movement of trees and flags:
- 10 km/h: Wind felt on face, wind vane begins to move
- 20 km/h: Small flags extended
- 30 km/h: Wind raises loose paper, large flags flap, small tree branches move
- 40 km/h: Small trees begin to sway, large flags extend and flap strongly
- 50 km/h: Large branches move, telephone wires whistle
- 60 km/h: Trees bend, walking against wind is hard
Protecting Yourself from Wind Chill and Frostbite
Strong winds make it easier to get cold injuries like frostbite and hypothermia. To stay safe:
- Dress in layers with a wind-resistant outer layer
- Cover exposed skin: face, ears, nose, fingers, and toes
- Limit time outdoors when wind chill is high risk or above
- Check face and extremities for numbness or whiteness
- Stay dry—wet skin freezes faster
- Stay informed with Environment Canada weather alerts