Wind Chill Calculator
Calculate wind chill from air temperature and wind speed with the 2001 NWS and Environment Canada formula, in °F or °C, with frostbite risk and time to frostbite.
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About this toolWhat is the Wind Chill Calculator?
Wind strips heat from exposed skin faster than still air does, so a breezy 10°F day feels far colder than a calm one. The Wind Chill Calculator turns air temperature and wind speed into the wind chill, the temperature on calm air that would cool your face at the same rate, and tells you how quickly frostbite can set in.
At 10°F with a 20 mph wind, the wind chill is -9°F (-23°C), which Environment Canada classes as a moderate frostbite risk. Drop to -20°F with a 25 mph wind and the wind chill is -51°F, where exposed skin can freeze in 5 to 10 minutes.
Enter temperature in °F or °C and wind in mph, km/h, m/s or knots. The calculator uses the formula native to your temperature unit, checks the conditions are inside the range where wind chill is defined and shows a table of wind chill at your temperature across a range of wind speeds.
- 2001 NWS formula in °F and Environment Canada formula in °C
- Wind in mph, km/h, m/s or knots with automatic conversion
- Valid-range checks (50°F or colder, wind above 3 mph) with a clear message
- Frostbite risk category and time to frostbite
- Table of wind chill across wind speeds
- Step-by-step working, shareable link and copy-ready summary
How to use the Wind Chill Calculator
- Choose °F or °C. Switching converts the temperature you entered.
- Enter the air temperature from your forecast or thermometer.
- Enter the wind speed and pick its unit: mph, km/h, m/s or knots. Use the forecast sustained wind, not gusts.
- Read the wind chill, the frostbite risk category and the time to frostbite.
- Check the table to see how the wind chill changes if the wind picks up or drops.
Worked examples
A blustery winter morning
Input
10°F, wind 20 mph
Output
Wind chill -9°F (-23°C), moderate risk
The wind takes 19°F off the felt temperature. Frostbite is possible with long exposure, so cover the face and hands.
A Canadian forecast in metric
Input
-15°C, wind 30 km/h
Output
Wind chill -26 (Environment Canada chart value), moderate risk
This matches the published Environment Canada table. Two degrees colder and the category becomes high risk.
Dangerous cold
Input
-20°F, wind 25 mph
Output
Wind chill -51°F (-46°C), very high risk: skin can freeze in 5 to 10 minutes
At this level, exposed skin needs to be covered completely and time outside kept short.
Outside the valid range
Input
55°F, wind 20 mph
Output
Not applicable: wind chill is defined only at 50°F or colder
Wind still feels cool on a mild day, but the index was built for cold-weather frostbite risk and is not used above 50°F.
Background and insight
The current wind chill index was adopted by the US National Weather Service and the Meteorological Service of Canada in 2001, developed by the Joint Action Group for Temperature Indices. It models heat loss from a human face walking into the wind, uses wind speed reduced from the standard 10 m (33 ft) anemometer height to face height, and assumes a clear night sky with no warming from the sun. It replaced the older Siple and Passel index, which exaggerated the chill.
In Fahrenheit, the NWS formula is WC = 35.74 + 0.6215T - 35.75V^0.16 + 0.4275T·V^0.16, with T in °F and V in mph. Environment Canada publishes the same model in metric: WC = 13.12 + 0.6215T - 11.37V^0.16 + 0.3965T·V^0.16, with T in °C and V in km/h. The index is only defined at or below 50°F (10°C) and for wind above 3 mph (4.8 km/h); outside that range the calculator explains why rather than giving a misleading figure.
Frostbite guidance follows Environment Canada's wind chill categories: low risk down to -9, moderate from -10 to -27, high from -28 to -39 (skin can freeze within 10 to 30 minutes), very high from -40 to -47 (5 to 10 minutes), severe from -48 to -54 (2 to 5 minutes) and extreme at -55 or colder (under 2 minutes), all in °C wind chill. The NWS chart marks the same first threshold: at a wind chill of -19°F, exposed skin can freeze in 30 minutes.
Common use cases
Dressing for the cold
Decide how much skin you can leave exposed for a commute, a run or a walk to school.
Winter sports and hiking
Plan ski days, ice fishing or mountain hikes around the frostbite timeline.
Outdoor work safety
Set warm-up break schedules for crews working in wind and cold.
School and event decisions
Check the wind chill against your organisation's cancellation thresholds.
Converting forecasts
Use wind in knots or m/s from marine and aviation forecasts and get a familiar number.
Tips and limitations
- Wind chill only affects exposed skin and wet surfaces. It cannot cool an object, a car or a pipe below the air temperature.
- Use sustained wind, not gusts, as forecasts and the formula do.
- Bright sunshine can make it feel 10 to 18°F warmer than the wind chill, according to the NWS.
- Wet skin or clothing loses heat much faster; stay dry.
- Children, older adults and people with circulation problems are more susceptible. This is an estimate, not medical advice.
Frequently asked questions
How is wind chill calculated?
The NWS formula is 35.74 + 0.6215T - 35.75V^0.16 + 0.4275T·V^0.16, with T in °F and V in mph. In Celsius and km/h, Environment Canada uses 13.12 + 0.6215T - 11.37V^0.16 + 0.3965T·V^0.16. Both describe the same 2001 model.
At what wind chill does frostbite occur?
Risk rises quickly below a wind chill of about -27°C (-17°F). At -28 to -39°C skin can freeze in 10 to 30 minutes, at -40 to -47°C in 5 to 10 minutes, at -48 to -54°C in 2 to 5 minutes, and below -55°C in under 2 minutes.
Why is there no wind chill above 50°F?
The index was designed to describe cold stress and frostbite risk, and the model is only valid for cold air. At or above 50°F (10°C), or with wind of 3 mph or less, the NWS does not report a wind chill.
Can wind chill freeze water or my car?
No. Wind speeds up cooling, but an object can only cool to the air temperature. If the air is 35°F, water will not freeze however strong the wind, even if the wind chill is 25°F.
What wind speed should I use?
Use the sustained wind speed from your forecast or a nearby weather station, which is measured 10 m (33 ft) above the ground. The formula already reduces it to face height.
What is the difference between wind chill and feels-like temperature?
Many apps show a "feels like" value that is the wind chill in cold weather and the heat index in hot, humid weather. Wind chill covers cold and wind only; the heat index covers heat and humidity.
Is there an in-depth guide to the Wind Chill Calculator?
Yes. “Heat Index and Wind Chill: How Feels-Like Temperatures Work” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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