About the Wind Chill Calculator
This wind chill calculator turns an air temperature and a wind speed into the "feels like" temperature that exposed skin experiences. It uses the wind chill index adopted by the US National Weather Service and Environment and Climate Change Canada in 2001, so the answer matches the wind chill numbers in North American forecasts.
Use it before winter runs, ski days, hunting trips, outdoor work shifts or a walk to school to judge how much skin to cover and how long it is safe to stay out. You can work in °F with mph or in °C with km/h or m/s, and the table shows how the wind chill falls as the wind picks up at your temperature. The risk band follows the Canadian government's frostbite guidance.
The formula is only defined for air temperatures at or below 50 °F (10 °C) and wind speeds above 3 mph (about 5 km/h), measured at the standard 10 m anemometer height. Outside that range wind chill has no official meaning, so the calculator shows the plain air temperature instead. Wind chill describes heat loss from skin; it does not cool objects such as car radiators or pipes below the actual air temperature.
With the default inputs, the wind chill (feels like) is 6.2. Change any value above to recalculate instantly.
How to use the wind chill calculator
- 1Choose °F with mph, or °C with km/h or m/s.
- 2Enter the air temperature from your forecast or thermometer.
- 3Enter the sustained wind speed (not gusts).
- 4Read the wind chill and the frostbite risk band.
- 5Check the table to see how much colder it would feel if the wind strengthens.
Formula and method
This is the wind chill temperature index introduced in November 2001 by the US National Weather Service and the Meteorological Service of Canada. It models the heat lost from a human face walking at about 3 mph into the wind, with the wind speed reduced from the 10 m anemometer height to face level, and reports the still-air temperature that would cause the same heat loss.
The calculator converts metric inputs to °F and mph, applies the NWS formula, and converts the result back, which agrees with Environment Canada's metric version (13.12 + 0.6215·T − 11.37·V^0.16 + 0.3965·T·V^0.16 with T in °C and V in km/h) to within about 0.05 °C, because both are rounded fits of the same model. The index is defined only for T ≤ 50 °F (10 °C) and V > 3 mph; outside that range the air temperature is returned. Risk bands use the Canadian wind chill risk categories.
- WC
- Wind chill temperature (°F)
- T
- Air temperature (°F)
- V
- Wind speed at 10 m height (mph)
Worked examples
0 °F with a 15 mph wind
WC = 35.74 + 0 − 35.75 × 15^0.16 + 0 = −19.4 °F (about −28.6 °C). The NWS wind chill chart shows the same −19 °F for this combination and notes that exposed skin can freeze in about 30 minutes.
−10 °C with a 30 km/h wind
−10 °C is 14 °F and 30 km/h is 18.64 mph. The formula gives −3.09 °F, which is −19.5 °C (Environment Canada's metric formula gives −19.5 too, within a few hundredths). That sits in the −10 to −27 moderate-risk band.
5 °F with a 25 mph wind
With V^0.16 = 25^0.16 ≈ 1.674, WC = 35.74 + 3.11 − 59.85 + 3.58 ≈ −17.4 °F, or −27.4 °C, at the cold end of the moderate band.
−25 °C with a 10 m/s wind
10 m/s is 22.37 mph and −25 °C is −13 °F. The wind chill is −40.3 °F = −40.1 °C, which rounds to −40: very high risk, with skin able to freeze in 5 to 10 minutes.
Mild 60 °F day with wind
Wind chill is only defined at or below 50 °F, so the calculator returns the air temperature of 60 °F and flags that the formula does not apply.
Frequently asked questions
What is the wind chill formula?+
The NWS formula is WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16, with T in °F and V in mph. The metric version used in Canada is 13.12 + 0.6215T − 11.37V^0.16 + 0.3965TV^0.16 with T in °C and V in km/h.
At what temperature does wind chill apply?+
The National Weather Service defines wind chill only for air temperatures at or below 50 °F (10 °C) and wind speeds above 3 mph. Environment Canada reports it when the temperature is 0 °C or below and the wind is at least 5 km/h.
Can wind chill freeze water or my car engine?+
No. Wind chill describes how fast skin loses heat. Wind speeds up cooling of objects, but an inanimate object such as a pipe or radiator can never be cooled below the actual air temperature by wind.
How fast can frostbite happen?+
According to Environment and Climate Change Canada, exposed skin can freeze in 10 to 30 minutes at wind chills of −28 to −39, in 5 to 10 minutes from −40 to −47, in 2 to 5 minutes from −48 to −54 and in under 2 minutes at −55 or colder (°C).
Why did the wind chill formula change in 2001?+
The old Siple–Passel index, based on how fast a plastic cylinder of water froze in Antarctica in the 1940s, exaggerated the chill. The 2001 index uses a model of heat loss from the human face, tested on volunteers in a wind tunnel, and reduces the 10 m forecast wind to face height (about 1.5 m).
What is the difference between wind chill and heat index?+
Wind chill combines cold and wind to describe faster heat loss from skin, while the heat index combines heat and humidity to describe how hard it is for sweat to cool you. Each applies in a different temperature range.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.