Enter the air temperature and wind speed to get the official wind chill — the temperature your exposed skin actually experiences — plus how long frostbite would take at that reading.
| Wind speed | Wind chill | Difference | Frostbite risk |
|---|
Calculated on your device using the published formula.
The 2001 NWS and Environment Canada equation used by weather services across North America.
Celsius or Fahrenheit, with wind in km/h, mph, metres per second or knots.
See the risk category and how long exposed skin can safely stay uncovered.
Wind chill needs only two measurements, and both are on every weather report.
Still air next to your skin forms a thin insulating layer. Wind strips that layer away and replaces it with colder air, so your body loses heat far faster than the thermometer suggests. Wind chill puts a number on that effect by asking a simple question: what still-air temperature would cause the same rate of heat loss from exposed skin?
The original 1945 formula was based on how fast water froze in plastic cylinders and badly overstated the effect. The modern equation is built on human trials with facial heat-loss sensors.
Wind chill is a physiological index. It never lowers the actual air temperature, so nothing freezes below the true reading.
Environment Canada issues warnings once wind chill passes -27, with frostbite times shortening sharply as the number falls.
Because the effect is about convective heat loss, a windproof outer layer restores much of the still-air insulation even without extra bulk.
Questions about the formula, its limits and frostbite risk.
The current North American formula, adopted in 2001, is: wind chill in Celsius = 13.12 + 0.6215T - 11.37V^0.16 + 0.3965T x V^0.16, where T is air temperature in Celsius and V is wind speed in km/h measured at 10 metres.
The official formula is only valid at or below 10 degrees Celsius (50 F) with wind above 4.8 km/h (3 mph). Outside that range the calculator reports the plain air temperature, because wind no longer makes the air feel meaningfully colder.
No. Wind chill describes heat loss from warm skin, so it only applies to people and animals. Water pipes and radiators cool to the actual air temperature no matter how hard the wind blows — wind only makes them reach it faster.
At a wind chill of about -28 C exposed skin can freeze in roughly 30 minutes. At -40 C that drops to about 10 minutes, and below -48 C it can take under 5 minutes.
They are opposites. Wind chill describes how much colder moving air makes you feel below 10 C, while the heat index describes how much hotter humid air makes you feel above about 27 C.