Wind Chill Calculator
How cold the air feels on exposed skin at a given temperature and wind speed, from the National Weather Service wind chill index, in °F or °C.
Result
Wind chill: 6.2 °FEstimate
For exposed skin at face height in shade. Sunshine makes it feel warmer; wet skin, colder.
- Colder than the air by
- 13.8 °FEstimate
https://calcgallery.com/weather/wind-chill-calculator/
Results come from the published equations applied to the values you enter. They are not electrical design, conductor sizing, laboratory safety or medical guidance. Weather indices describe a standard person in standard conditions and are not a forecast. Where codes apply, local rules vary and must be checked. Read the full disclaimer
How to use the Wind Chill Calculator
- Enter the air temperature in °F or °C.
- Enter the wind speed in mph, km/h or m/s, as a weather report gives it.
- Read the wind chill and how much colder than the air it feels.
The formula
With the air temperature T in °F and the wind speed V in mph:
wind chill = 35.74 + 0.6215 T − 35.75 V^0.16 + 0.4275 T V^0.16This is the National Weather Service index introduced in 2001, developed with Environment Canada. The coefficients come from a model of heat loss from the human face. Temperatures entered in Celsius are converted to Fahrenheit exactly, including the offset between the two scales, and the result converted back.
Where it applies
The index is defined only for air at or below 50 °F (10 °C) and wind above 3 mph (4.8 km/h). Wind speed is the standard 10-metre measurement used in weather reports; the formula adjusts it to face height itself.
What it does not tell you
Wind chill is about skin. Sunshine can make it feel several degrees warmer, and wet skin or clothing loses heat much faster. Pipes, engines and water cannot be cooled below the actual air temperature by wind, however strong.
With your numbers
- T = 20 °F, V = 15 mph
- 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16 = 6.22 °F
Quick reference
For exposed skin at face height in shade. Sunshine makes it feel warmer; wet skin, colder.
| Example | Wind chill |
|---|---|
| 20 °F, 15 mph | 6.2 °F |
| 0 °F, 20 mph | -22 °F |
| 40 °F, 5 mph | 36.5 °F |
| −10 °C, 30 km/h | -19.5 °C |
| 70 °F, 10 mph | 70 °F |
| 20 °F, 2 mph | 20 °F |
| −20 °F, 30 mph | -53 °F |
Common questions about the Wind Chill Calculator
- What does wind chill actually measure?
- How fast exposed skin loses heat. Wind strips away the thin layer of warmer air next to the skin, so it cools faster than it would in still air at the same temperature. The index expresses that as the still-air temperature that would cool skin at the same rate. It does not change the air temperature, and it cannot cool an object below the air temperature.
- Why is no wind chill shown above 50 °F?
- The National Weather Service defines the index only at or below 50 °F (10 °C) and for winds above 3 mph. Outside that range the formula still returns a number, but it means nothing: at 70 °F with a 10 mph wind it gives about 71 °F, warmer than the air. The page shows the air temperature instead and says why.
- How does this compare with the old wind chill chart?
- The 2001 index replaced one from the 1940s that exaggerated the effect of wind. The current formula models heat loss from the face, at the height of an adult's face and assuming no sunshine, and gives warmer figures than the old chart in strong wind.
- Does the formula change in Celsius?
- The index has a published metric form too, and it agrees with the Fahrenheit form to within a few hundredths of a degree. This page uses the Fahrenheit form throughout and converts Celsius and km/h entries exactly, so the same conditions give the same answer in either system.