How cold exposed skin feels once wind is stripping away the thin layer of warm air around you. The thermometer reading does not change — the rate of heat loss does.

When does the wind chill formula apply?

At or below 50°F (10°C) with wind above 3 mph. Outside that range the US National Weather Service formula is not valid.

Does wind chill affect objects like car engines?

No. Wind speeds up cooling toward the air temperature but cannot take anything below it. Only things generating their own heat, like people and animals, feel wind chill.

Wind Chill Calculator

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

Frequently asked questions

What is wind chill?: How cold exposed skin feels once wind is stripping away the thin layer of warm air around you. The thermometer reading does not change — the rate of heat loss does.
When does the wind chill formula apply?: At or below 50°F (10°C) with wind above 3 mph. Outside that range the US National Weather Service formula is not valid.
Does wind chill affect objects like car engines?: No. Wind speeds up cooling toward the air temperature but cannot take anything below it. Only things generating their own heat, like people and animals, feel wind chill.