How this calculator works
- Step 1Convert°F and mphThe formula is defined in US units.
- Step 2Wind factorV^0.16Wind speed raised to the power 0.16.
- Step 3Wind chill35.74 + 0.6215T − …The NWS formula, then back to °C.
Wind carries heat away from exposed skin, so a windy day feels colder than the thermometer shows. Wind chill puts a temperature on that feeling.
The calculator uses the formula behind the US National Weather Service Wind Chill Chart, in force since November 2001.
Worked example: −10 °C in a 30 km/h wind
- NWS (2001)
WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16
- TTemperature −10 °C = 14 °F
- VWind speed 30 km/h ≈ 18.64 mph
- Convert−10 × 9/5 + 32; 30 ÷ 1.60934414 °F, 18.64 mph
- FormulaNWS wind chill−3 °F
- Wind chillback to °C−19 °C (−3 °F)
The wind makes it feel about 9 °C colder than the air, which is why exposed skin is at risk sooner.
More wind, more chill
Read the result
The NWS chart lists 0 °F in a 15 mph wind as −19 °F; the calculator gives −19 °F.
Even near freezing the wind matters: 0 °C in a 20 km/h breeze feels like −5 °C (23 °F).
Assumptions and limits
- Cold onlyDefined at or below 10 °C (50 °F).
- Some windDefined above 4.8 km/h (3 mph).
- ShadeBright sun can feel 10–18 °F warmer.
- People and animalsWind chill does not cool objects below the air temperature.
Related weather tools
Wind chill is how cold it feels. Heat and moisture have their own measures.
For hot, humid days, use the heat index calculator. The dew point calculator shows when moisture will condense.
Common mistakes
Mistake: Using wind chill on a warm day.
Instead: Above 10 °C, use the air temperature or the heat index.
Mistake: Expecting pipes to freeze at the wind chill.
Instead: Objects only cool to the air temperature.
Mistake: Mixing gust and average speeds.
Instead: Use the sustained wind speed from the forecast.
Checking the method
All 216 values of the NWS Wind Chill Chart are reproduced, and each golden case is re-worked in 40-digit decimal.
An independent script recomputes the formula with Python’s decimal module and matches every printed chart value to the nearest °F.
Read how we test our calculators, or browse more health calculators.