Enter air temperature and wind speed to calculate the Wind Chill Index — the perceived decrease in temperature felt by the skin due to wind.

Wind Chill: 4.0 °F

Note: Formula valid for temperatures ≤ 50°F and wind speeds ≥ 3 mph. Below that, wind chill is not defined.

What is Wind Chill Index?

The Wind Chill Index (WCI) is a measure of the perceived drop in air temperature felt by the human body due to the combined effect of cold and wind. When wind blows across exposed skin, it accelerates heat loss by convection, making the air feel colder than the actual thermometer reading.

This index is crucial for safety during winter activities, as it helps predict the risk of frostbite and hypothermia. The modern formula used in the United States and Canada was revised in 2001 by the Joint Action Group on Wind Chill. It is based on modern heat transfer theory and uses a standard human face model. The formula is valid for air temperatures at or below 50°F and wind speeds above 3 mph. At lower wind speeds or higher temperatures, the wind chill effect is negligible or non-existent.

The calculation uses air temperature in Fahrenheit and wind speed in miles per hour (mph). The result is expressed as an equivalent temperature (°F), which represents the cooling effect of the wind on exposed skin.

How to Use This Calculator

1. Enter Air Temperature: Type the current air temperature in degrees Fahrenheit (°F) into the first field. Valid range is up to 50°F.
2. Enter Wind Speed: Type the wind speed in miles per hour (mph) into the second field. Must be at least 3 mph for the formula to apply.
3. Calculate: Click the “Calculate Wind Chill” button or press Enter on your keyboard to see the result.
4. Reset: Use the “Reset” button to clear your inputs and revert to the default example.
5. Interpretation: The result shows the “feels-like” temperature. For example, if the air is 20°F with a 15 mph wind, it feels like 4°F. Use this information to dress appropriately and limit time outdoors.