What this calculator does

This wind chill calculator estimates how cold exposed skin feels when cold air is combined with moving wind. The number helps explain cold-stress risk by translating extra convective heat loss into a more intuitive feels-like temperature.

A calm winter day and a windy winter day can have the same thermometer reading but very different human effects. Wind strips away the thin layer of warmer air that forms near the skin, so the body loses heat faster. Wind chill is therefore a human heat-loss index, not a description of what happens to inanimate objects.

Inputs explained

• Air temperature: Enter the actual air temperature in F or C.
• Wind speed: Enter the wind speed and choose the correct speed unit when available on the page.
• Unit selector: The calculator applies the correct U.S. or metric formula based on the temperature scale you use.

How it works / method

The page uses the standard wind chill formulas commonly associated with National Weather Service guidance. For U.S. units, the model is valid for temperatures at or below 50 F and wind speeds above 3 mph. For metric inputs, the matching cold-weather form is applied below 10 C with sufficiently strong wind. Outside those ranges, the model is intentionally treated as invalid because it was not built for mild weather.

Formula used

For metric inputs, the calculator uses the equivalent Celsius form. T is air temperature and V is wind speed. The model is designed for exposed skin and open-air cold stress, not sheltered conditions or indoor environments.

Step-by-step example

Suppose the air temperature is 20 F and the wind speed is 20 mph. The dry air temperature is cold, but the human cooling rate becomes much more severe once wind is added.

1. Enter 20 for temperature and choose F.
2. Enter 20 for wind speed in mph.
3. The result falls near 4 F as a wind chill value.
4. That means exposed skin loses heat roughly like it would on a calmer day around 4 F.
5. If clothing is wet or skin is exposed, frostbite risk rises faster than the thermometer alone suggests.

Use cases

• Checking whether exposed outdoor work should be reduced, delayed, or paired with heavier cold-weather clothing.
• Explaining forecast cold stress to runners, cyclists, utility crews, and winter travelers.
• Comparing two winter forecast periods where the air temperature is similar but wind exposure is very different.
• Teaching the difference between measured air temperature and a derived human-exposure index.

Assumptions and limitations

• The wind chill model is only meant for cold-weather conditions inside its published validity range.
• Shelter, sunshine, terrain, face coverings, moisture, and metabolic heat can all change how a person actually feels.
• The result should not be used as a blanket trigger for all industrial or medical decisions without local safety protocols.
• Wind chill does not account for solar radiation and is not a summer or warm-season comfort index.

For heat exposure, use heat index, apparent temperature, humidex, or WBGT instead of trying to interpret wind chill outside the cold-weather regime.

Sources & references

• NOAA National Weather Service - Heat index guidance
• NOAA National Weather Service - Wind chill chart and formula
• NOAA National Weather Service - Wet Bulb Globe Temperature overview
• Bureau of Meteorology - Apparent temperature background
• Bureau of Meteorology - Apparent temperature glossary
• Environment and Climate Change Canada - Humidex guidance
• Schema.org - FAQPage and WebApplication vocabulary