Wind chill is how cold the air actually feels on exposed skin once the wind is factored in. Moving air carries away the thin layer of warmth your body builds up, so heat is lost faster — a 20°F day with a stiff wind can feel like 5°F. It is the cold-weather counterpart to the heat index.

How is wind chill calculated?

The NWS wind chill formula combines the air temperature and wind speed and is only defined for temperatures at or below 50°F and wind above 3 mph. Above those thresholds, wind does not meaningfully cool the human body.

At what wind chill does frostbite happen?

At a wind chill around −19°F, frostbite can occur on exposed skin in about 30 minutes. At −36°F it drops to roughly 10 minutes, and below −60°F to about 5 minutes. Colder wind chills shorten the safe exposure time dramatically.

Does wind chill affect objects or just people?

Wind chill only describes heat loss from a warm body like exposed skin — it cannot cool an object below the actual air temperature. Your car engine or a pipe will not freeze faster than the real temperature allows, but bare skin loses heat as if it were that much colder.

What Is Wind Chill? — How Cold It Really Feels

What Is Wind Chill? — How Cold It Really FeelsWind chill is how cold the air feels on exposed skin once wind is factored in. When the NWS formula applies, why it is a "feels like" temperature not a real one, and the frostbite-risk timetable.Wind chill is how cold the air actually feels on exposed skin once you factor in the wind. Moving air strips away the thin layer of warmth your body builds up, carrying heat away faster — so a 20°F day with a stiff wind can feel like 5°F. It is the cold-weather counterpart to the heat index, and it drives Wind Chill Advisories and Warnings.When it appliesThe NWS wind chill formula is only defined for air temperatures at or below 50°F and wind speeds above 3 mph. Above those thresholds, wind does not meaningfully cool the human body.Wind chill is a "feels like" value, not a real temperature. It measures heat loss from bare skin and cannot cool an object below the actual air temperature — your car engine will not freeze faster — but exposed skin loses heat as if it were that much colder.Frostbite risk by wind chill

Above 0°F: uncomfortable; frostbite unlikely for most people

0 to −18°F: frostbite possible with prolonged exposure

−19 to −35°F: frostbite on exposed skin in about 30 minutes

−36 to −60°F: frostbite in about 10 minutes

Below −60°F: frostbite in about 5 minutes

Wind chill is the winter mirror of the heat index — both translate raw temperature into how it actually feels to a human body.

Frequently asked questions

What is wind chill?: Wind chill is how cold the air actually feels on exposed skin once the wind is factored in. Moving air carries away the thin layer of warmth your body builds up, so heat is lost faster — a 20°F day with a stiff wind can feel like 5°F. It is the cold-weather counterpart to the heat index.
How is wind chill calculated?: The NWS wind chill formula combines the air temperature and wind speed and is only defined for temperatures at or below 50°F and wind above 3 mph. Above those thresholds, wind does not meaningfully cool the human body.
At what wind chill does frostbite happen?: At a wind chill around −19°F, frostbite can occur on exposed skin in about 30 minutes. At −36°F it drops to roughly 10 minutes, and below −60°F to about 5 minutes. Colder wind chills shorten the safe exposure time dramatically.
Does wind chill affect objects or just people?: Wind chill only describes heat loss from a warm body like exposed skin — it cannot cool an object below the actual air temperature. Your car engine or a pipe will not freeze faster than the real temperature allows, but bare skin loses heat as if it were that much colder.

Part of the BloomWX learn library — beginner-friendly explainers covering every surface of the BloomWX weather dashboard. Open BloomWX to see live data for any U.S. county.