Weather / 02
Wind Chill Calculator
Work out how cold it feels from the air temperature and wind speed, with the formula the US and Canadian weather services use, and how fast exposed skin can freeze.
Wind Chill Calculator: The calculator uses the wind chill formula adopted by the US National Weather Service and Environment Canada in 2001, which models heat loss from a face walking into the wind. It applies at 50 °F (10 °C) or colder with wind above 3 mph (5 km/h). The risk bands and frostbite times are Environment Canada's: exposed skin can freeze in 10 to 30 minutes from a wind chill of −28, and in under 2 minutes at −55 or colder. Runs 100% locally in your browser with zero server file uploads.
- Category
- Everyday tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
How the formula was made
The current wind chill index replaced an older one from the 1940s that exaggerated the cold. It was developed by scientists in the United States and Canada and tested on volunteers in a wind tunnel, and models a face at about 1.5 metres above the ground, walking into the wind, on a clear night.
Bright sunshine can make it feel several degrees warmer than the wind chill suggests; wet skin or clothing makes it feel colder.
Planning time outside
Darkness comes early in winter and the temperature falls after sunset; sunrise and sunset gives the times for your place. In summer, the heat index calculator does the same job for heat and humidity.
How to use it
- Choose °F or °C and your wind speed unit.
- Enter the air temperature and the wind speed.
- Read the wind chill and the frostbite risk.
Privacy & limitations
Everything is calculated in your browser; only your choice of units is remembered.
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Frequently asked questions
What does wind chill mean?
How cold the air feels on exposed skin, given the wind. Wind strips away the thin layer of warm air next to the skin, so the body loses heat faster; a wind chill of −20 means skin loses heat as fast as it would at −20 in calm air.
Can wind chill freeze water pipes or a car?
No. Objects without their own heat cool faster in wind but never below the air temperature. If the air is above freezing, wind cannot freeze them, whatever the wind chill.
Which wind speed should I use?
The sustained wind speed from a forecast or weather station, measured 10 metres above the ground, which is how the formula is designed. Gusts are briefly stronger and would overstate the chill.
How do I protect myself at high risk?
Cover exposed skin, wear layers with a windproof outer layer, and keep moving. Watch for frostbite: numbness, and skin turning white or greyish-yellow and feeling hard or waxy. Warm it gently and get medical help for anything beyond the earliest stage.
Free tool · runs in your browser · no account required