Wind Chill Calculator
Calculate the wind chill or 'feels like' temperature from air temperature and wind speed using the official NWS formula, with the frostbite risk it implies.
Cómo usar esta calculadora
- 1Choose Fahrenheit/mph or Celsius/km/h units.
- 2Enter the actual air temperature.
- 3Enter the wind speed.
- 4Read the 'feels like' wind chill and the frostbite risk for exposed skin.
Cómo funciona
Wind chill (NWS 2001)
°F: WC = 35.74 + 0.6215T − 35.75·V^0.16 + 0.4275·T·V^0.16 °C: WC = 13.12 + 0.6215T − 11.37·V^0.16 + 0.3965·T·V^0.16 T = air temperature, V = wind speed valid for T ≤ 50°F (10°C) and V > 3 mph (4.8 km/h)
Wind chill quantifies how cold the air feels because of the wind, expressed as an equivalent 'feels like' temperature. Your body constantly warms a thin boundary layer of air right at the skin; wind blows that warmed layer away and replaces it with cold air, so heat is stripped from the body faster and the skin cools more quickly than in still air. The current formula, adopted by the US National Weather Service and Environment Canada in 2001, was derived from measurements of heat loss from human faces and models the skin's cooling more realistically than the older 1945 version. It combines the air temperature and the wind speed raised to the power 0.16, which captures how the cooling effect grows quickly at first and then levels off as wind increases. The formula is only defined for cold, windy conditions — at or below 50°F with a real breeze — because that is where wind chill is a meaningful hazard.
Ejemplo resuelto
At an air temperature of 20°F with a 20 mph wind, the wind chill is about 4°F — it feels 16 degrees colder than the thermometer reads. The wind isn't making the air colder; it's carrying heat away from exposed skin fast enough that the skin behaves as if the surrounding air were 4°F.
Wind Chill Calculator: la guía completa
What wind chill actually measures
Wind chill is one of the most misunderstood numbers in a weather forecast. It is not a claim that the wind lowers the air temperature — a thermometer in the shade reads the same whether the air is still or howling. What wind chill measures is the rate at which the wind removes heat from warm exposed skin, translated into the temperature of still air that would cool the skin at the same rate. It is a statement about how cold it feels and how fast you lose body heat, not about the physical temperature of the air.
The mechanism is the thin boundary layer of air your body warms right against the skin. In still air, this insulating layer builds up and slows further heat loss. Wind constantly sweeps it away, exposing the skin to fresh cold air and accelerating the loss of heat. The stronger the wind, the faster this happens, which is why a bitter wind on a merely chilly day can feel — and be, for the purposes of frostbite and hypothermia — far more dangerous than the thermometer suggests.
The formula and why it changed
The wind-chill index most of North America uses today dates from 2001, replacing an earlier formula from 1945 that was based on how fast water froze in a container, not on human physiology. The old version dramatically overstated the effect, producing alarmingly low 'feels like' numbers that did not match how cold people actually got. The modern formula was developed from clinical trials measuring heat loss from the faces of volunteers in a chilled wind tunnel, and it models a walking pace and a typical human face at a standard height.
The equation combines air temperature with wind speed raised to the power 0.16 — a fractional exponent that reflects a real feature of the physics: wind chill worsens rapidly as a light breeze picks up, but additional wind beyond about 25–30 mph adds progressively less, because the boundary layer is already being stripped away efficiently. This is why the difference between still air and a 15 mph wind is dramatic, while the difference between 30 and 45 mph is comparatively modest. The formula only applies in cold, breezy conditions; on a warm day or in near-calm air, wind chill is not defined and the air temperature is what you feel.
Frostbite, safety, and the limits of the number
The practical value of wind chill is as a warning about how quickly exposed skin can freeze. At a wind chill around −18°F, frostbite can develop on exposed skin in roughly half an hour; near −35°F, in about ten minutes; and below −60°F, in five minutes or less. These thresholds are why weather services issue wind chill advisories and warnings — the number is a proxy for how urgently you need to cover up, and it drives real decisions about school closures, outdoor work, and cold-weather recreation.
It is important to remember what wind chill does and does not tell you. It applies to bare skin and to heat loss from the body, so it is a good guide to frostbite and to how cold you will feel, but it does not change how fast your car's radiator freezes or a pipe bursts — those depend on the actual air temperature, which cannot fall below what the thermometer reads no matter how hard the wind blows. Wind chill also assumes you are exposed; proper clothing that traps a still layer of air near the skin defeats much of the effect, which is precisely why dressing in windproof layers is the first defence against a bitter wind.
Preguntas frecuentes
What is wind chill?
Wind chill is the 'feels like' temperature that accounts for how wind strips heat from exposed skin. It's not a real drop in air temperature — a thermometer reads the same — but it reflects how much faster your body loses heat, and how quickly frostbite can set in, when it's cold and windy.
How is wind chill calculated?
By the 2001 NWS formula, which combines air temperature and wind speed raised to the power 0.16. In Fahrenheit and mph: WC = 35.74 + 0.6215T − 35.75·V^0.16 + 0.4275·T·V^0.16. It's valid only at or below 50°F with wind above 3 mph.
Does wind chill affect objects like pipes and cars?
No. Wind chill only describes heat loss from warm bodies like exposed skin. Inanimate objects can't cool below the actual air temperature, however strong the wind — a pipe or radiator freezes based on the real temperature, not the wind chill. Wind only makes them reach that temperature faster.
How quickly does frostbite happen?
It depends on the wind chill. Around −18°F, exposed skin can get frostbite in about 30 minutes; near −35°F, in about 10 minutes; and below −60°F, in 5 minutes or less. These thresholds are why wind chill warnings are issued — they signal how urgently to cover exposed skin.