Calculate standard wind chill from air temperature and wind speed, or assess a known wind chill using published exposed-skin frostbite-risk bands in °F/°C and mph/km/h.
Wind Chill Formula (Used to Estimate Frostbite Risk)
This calculator uses the standard wind chill temperature equation to estimate how cold it feels on exposed skin when wind is present. Frostbite risk guidance is commonly expressed in terms of wind chill and exposure time.
Variables:
- WCT is the wind chill temperature (in degrees Celsius)
- T is the air temperature in degrees Celsius
- V is the wind speed in km/h
Important: The wind chill equation is intended for air temperatures at or below 10°C (50°F) and wind speeds above 4.8 km/h (3 mph). For warmer temperatures or very light winds, wind chill is generally taken to be the same as the actual air temperature.
Risk-band source and limit: The calculator uses Environment and Climate Change Canada's published bands: -28 to -39 (10 to 30 minutes), -40 to -47 (5 to 10 minutes), -48 to -54 (2 to 5 minutes), and -55 or colder (less than 2 minutes). These are exposed-skin risk estimates, not a diagnosis or frostbite-severity grade. Sustained winds over 50 km/h can shorten the listed times.
What is Frostbite?
Frostbite is a type of injury caused by freezing of the skin and underlying tissues, primarily affecting the fingers, toes, nose, ears, cheeks, and chin due to exposure to cold temperatures. It may begin with a cold and prickly feeling, followed by numbness and changes in skin color (often pale/white, then possibly bluish or blotchy). Severe cases can lead to permanent damage or amputation. Seek medical attention if frostbite is suspected.
How to Estimate Frostbite Risk
The steps below outline how this calculator estimates wind chill temperature and a frostbite risk category:
- Determine the air temperature (T) and convert it to °C if needed.
- Determine the wind speed (V) and convert it to km/h if needed.
- If T > 10°C or V < 4.8 km/h, use WCT ≈ T (wind chill is typically not applied outside those ranges).
- Otherwise, compute V0.16.
- Apply the wind chill formula to compute WCT.
- Use WCT to place conditions into an approximate frostbite risk/time-to-frostbite category (for exposed skin).
Example Problem:
Air Temperature (T) = -10°C
Wind Speed (V) = 20 km/h
Compute wind chill temperature:
V0.16 = 200.16 ≈ 1.615
WCT = 13.12 + 0.6215(-10) - 11.37(1.615) + 0.3965(-10)(1.615) ≈ -17.86°C
Since WCT ≈ -17.9°C (warmer than -28°C), this falls in a lower frostbite-risk category (frostbite generally not expected within 30 minutes), though prolonged exposure can still be dangerous.