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Wind Chill Calculator: What the Temperature Feels Like
Enter the air temperature and the wind speed. The calculator applies the North American wind chill index of 2001 and gives the feels-like temperature, valid for cold air and wind above walking pace.
The 2001 wind chill formula
In 2001 the US National Weather Service and Environment Canada adopted an updated wind chill index based on heat-loss models of the human face and on trials with volunteers in a wind tunnel. In US units, with temperature T in degrees Fahrenheit and wind speed V in miles per hour, it is:
WC = 35.74 + 0.6215 T − 35.75 V0.16 + 0.4275 T V0.16
The metric version, with T in degrees Celsius and wind speed v in kilometers per hour, is WC = 13.12 + 0.6215 T − 11.37 v0.16 + 0.3965 T v0.16. The wind speed is the speed at the standard 10 meter height, scaled down in the model to a walking-height equivalent.
When the formula applies
The index is valid for air temperatures at or below 50 °F (10 °C) and for wind speeds above 3 mph (about 4.8 km/h). Outside that range the calculator reports an error instead of a number, because the physical model no longer holds. With no wind there is no wind chill, and in warm weather the index is meaningless. For hot conditions, see the heat index calculator instead.
| Air temp | Wind | Wind chill |
|---|---|---|
| 30 °F | 10 mph | about 21 °F |
| 0 °F | 15 mph | about −19 °F |
| 0 °C | 20 km/h | about −5 °C |
What the number means
- It is a feels-like value for exposed skin. It assumes a face in shade and does not include sunshine, humidity or clothing.
- It does not alter real temperatures. A car radiator or water pipe cools only to the air temperature, though it gets there faster in wind.
- Heat loss rises with wind. That is why risk of frostbite and hypothermia depends on both numbers together.
Official weather services publish warnings and the exposure times used locally. Follow those rather than a rule of thumb, and take extra care with children, older adults, people with circulatory conditions, and anyone who is wet or working hard outdoors.
Limits and safety
This calculator is educational and is not a safety service. The index is a model of average heat loss and individuals differ. Sunshine can make it feel warmer, while wet clothing, fatigue and hunger make it feel much colder. Cover exposed skin, dress in layers, and move to shelter if you notice numbness, shivering that will not stop, confusion or clumsiness. In severe cold, rely on warnings from your local weather service and on emergency guidance, and seek medical help for suspected frostbite or hypothermia.
Worked example
An air temperature of 0 °F with a 15 mph wind.
Inputs
| Units | Fahrenheit and mph |
|---|---|
| Air temperature (°F or °C) | 0 |
| Wind speed (mph or km/h) | 15 |
Result
Feels like -19.4 °F on exposed skin, which is 19.4 degrees colder than the air temperature.
| Wind chill | -19.4 °F / -28.6 °C |
|---|---|
| Air temperature | 0.0 °F |
| Wind speed | 15.0 mph |
- Wind chill describes heat loss from exposed skin. It does not change the actual temperature of objects such as pipes or car engines, which cannot fall below the air temperature.
Estimating note: Quantities and ratings here are estimates for planning and learning. Products, local codes and site conditions differ, so check manufacturer data and local regulations, and use a qualified professional for electrical, structural or safety-critical work.
Frequently asked questions
How is wind chill calculated?
It is computed from air temperature and wind speed with a formula adopted in 2001: 35.74 plus 0.6215 times temperature, minus 35.75 times wind to the power 0.16, plus 0.4275 times temperature times wind to the same power.
At what temperature does wind chill apply?
The index is valid at 50 degrees Fahrenheit (10 degrees Celsius) and below, with wind above 3 mph. Outside that range the formula does not describe skin heat loss.
Can wind chill freeze water above 32 °F?
No. Wind chill describes heat loss from skin. Objects cool only down to the air temperature, so water does not freeze above its freezing point however strong the wind.
Is wind chill the same as the feels-like temperature?
In cold weather it is the usual feels-like number. In hot weather, services use the heat index instead, which accounts for humidity rather than wind.
Does the 2001 formula differ from the older one?
Yes. The older Siple and Passel index overstated cold. The 2001 version is based on newer heat-loss modelling and trials, and it gives milder values at the same inputs.
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References and sources
- US National Weather Service and Environment Canada: Wind Chill Temperature Index (2001 revision). Link