Wind Chill Calculator

1. Select your unit system. US users: choose °F and mph. Most other countries: choose °C and km/h.
2. Enter the air temperature. Use the current air temperature from a weather service. Wind chill only applies when temperatures are at or below 50°F (10°C).
3. Enter the wind speed. Use the sustained wind speed, not gusts. Wind speeds below 3 mph have negligible effect on perceived temperature.
4. Read the result. The "feels like" temperature is what the cold and wind feel like on exposed skin. The frostbite risk indicator tells you how quickly exposed skin could freeze at those conditions.

The National Weather Service uses the following formula, adopted in 2001 and derived from human clinical trials:

Wind Chill (°F) =
  35.74
  + 0.6215 × T
  - 35.75 × V^0.16
  + 0.4275 × T × V^0.16

Where:
  T = Air temperature in °F
  V = Wind speed in mph

The formula is valid for temperatures at or below 50°F and wind speeds of 3 mph or higher. Outside those ranges, wind chill is not calculated.

Example: Temperature = 20°F, Wind = 15 mph:

V^0.16 = 15^0.16 = 1.699

WC = 35.74 + 0.6215×20 - 35.75×1.699 + 0.4275×20×1.699
   = 35.74 + 12.43 - 60.74 + 14.53
   = 1.96°F ≈ 2°F

So 20°F with a 15 mph wind feels like 2°F on exposed skin. That is a perceived temperature drop of 18°F from the actual temperature.