Free tool · Training
Wind chill calculator for training in the cold
Short answer
Wind chill is how cold it feels on exposed skin once wind is counted. At 0 °F (-18 °C) with a 15 mph wind, the National Weather Service formula gives -19 °F (-29 °C), cold enough for exposed skin to freeze in 30 minutes. The formula applies at 50 °F (10 °C) or colder with wind above 3 mph.
Last reviewed 27 October 20261 published sourcesNot medical advice
Reps keeps track of this for you on iPhone, iPad and Apple Watch.
Get Reps freeWind chill calculator
Use the air temperature and sustained wind speed from a weather app or station.
Enter the temperature and wind speed to see the wind chill.
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| Air temperature | 5 mph | 10 mph | 20 mph | 30 mph | 40 mph |
|---|---|---|---|---|---|
| 40 °F (4 °C) | 36 | 34 | 30 | 28 | 27 |
| 30 °F (-1 °C) | 25 | 21 | 17 | 15 | 13 |
| 20 °F (-7 °C) | 13 | 9 | 4 | 1 | -1 |
| 10 °F (-12 °C) | 1 | -4 | -9 | -12 | -15 |
| 0 °F (-18 °C) | -11 | -16 | -22 | -26 | -29 |
| -10 °F (-23 °C) | -22 | -28 | -35 | -39 | -43 |
| -20 °F (-29 °C) | -34 | -41 | -48 | -53 | -57 |
The National Weather Service formula
Wind chill (°F) = 35.74 + 0.6215T − 35.75(V^0.16) + 0.4275T(V^0.16), with T in °F and V in mph. It is defined only for temperatures at or below 50 °F and wind speeds above 3 mph (National Weather Service).
The Weather Service's chart marks how quickly frostbite can set in; at a wind chill of -19 °F, exposed skin can freeze in 30 minutes (National Weather Service).
Training in the cold
For summer sessions, use the heat index calculator instead. Whatever the weather, pacing by heart rate keeps your effort in check; set your ranges with the heart rate zone calculator.
Know the weather before you go
Reps looks at the weather before your run, so you know what you are heading into before you lace up.
Free to download · iPhone, iPad and Apple Watch
Common questions
How is wind chill calculated?
The National Weather Service formula is wind chill (°F) = 35.74 + 0.6215T − 35.75(V^0.16) + 0.4275T(V^0.16), where T is the air temperature in °F and V the wind speed in mph. This calculator converts °C and km/h for you.
What wind chill causes frostbite?
The National Weather Service chart shows that at a wind chill of -19 °F (-28 °C), for example 0 °F air with a 15 mph wind, exposed skin can freeze in 30 minutes. Colder wind chills shorten that time.
Why is there no wind chill above 50 °F?
The National Weather Service defines wind chill only at 50 °F or colder with wind above 3 mph. In warmer weather, the heat index is the feels-like measure that matters.
Sources
Figures on this page were checked against these publications on 27 October 2026.
- National Weather Service. Wind chill chart. NOAA. www.weather.gov/safety/cold-wind-chill-chart
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