How wind chill is calculated
Moving air strips heat from exposed skin faster than still air, so a cold day feels colder when the wind picks up. Wind chill puts a single number on that felt temperature.
This uses the U.S. National Weather Service formula, which combines the air temperature and wind speed. Both the temperature and the wind term shape the result, which is why a small rise in wind can drop the felt temperature sharply.
- Inputs are temperature in Fahrenheit and wind speed in miles per hour.
- The answer is shown in both Fahrenheit and Celsius.
Reading the result
The figure is how cold the air feels on bare skin, not the actual thermometer reading. The lower it goes, the faster heat is lost and the sooner frostbite can set in on exposed areas.
Where it applies
The formula is designed for cold, windy conditions and is only meaningful within its valid range.
- Valid at temperatures of 50°F or below.
- Valid for wind speeds above 3 mph.
- Outside that range the number stops being reliable.
Important note
Wind chill describes air conditions only and assumes dry skin; getting wet or being in the sun changes how cold you actually feel. This is general weather guidance, not medical advice, so use real symptoms and local warnings to judge cold-exposure risk and seek care when needed.
Formula
35.74 + 0.6215·T − 35.75·V^0.16 + 0.4275·T·V^0.16