How do I calculate wind chill?
Wind chill combines air temperature and wind speed into a single 'feels like' number using the NOAA formula WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16, where T is temperature in °F and V is wind speed in mph. Example: at 30°F with a 20 mph wind, the wind chill is about 17.4°F.
Steps to calculate wind chill
- Enter the air temperature, choosing °F or °C.
- Enter the wind speed, choosing mph or km/h.
- The calculator converts both values to °F and mph internally, since that is what the NOAA formula requires.
- If temperature is above 50°F (10°C) or wind is below 3 mph (5 km/h), the formula is not applied — wind chill is only meaningful in cold, windy conditions.
- Within the valid range, the calculator applies the NOAA formula and shows the result in your chosen temperature unit, plus the other unit for reference.
Formula
WC = 35.74 + 0.6215T - 35.75 x V^0.16 + 0.4275 x T x V^0.16 (T in F, V in mph; valid for T <= 50F and V >= 3mph)
- T = air temperature in degrees Fahrenheit
- V = wind speed in miles per hour
- WC = wind chill temperature in degrees Fahrenheit, the 'feels like' value
Quick wind chill answers
What is the wind chill at -10°C with a 30 km/h wind?
About -19.5°C (-3.1°F) — the NOAA formula converts this internally to °F/mph (14°F, 18.6 mph) and back.
What is the wind chill at 0°F with a 20 mph wind?
About -22.0°F (-30.0°C).
What is the wind chill at 30°F with a 20 mph wind?
About 17.4°F (-8.1°C) — this calculator's default example.
Below what temperature does wind chill apply?
50°F (10°C) or below — above that, the NOAA formula's assumptions no longer hold, so wind chill values are not published for warmer temperatures.
What is the minimum wind speed for the wind chill formula to apply?
3 mph (about 5 km/h) — below that, the formula becomes unstable and can show a 'feels like' value warmer than the actual temperature, which isn't physically meaningful.
Does wind chill measure how fast car engines or water actually cool?
No — wind chill only describes how cold exposed human skin feels; it doesn't change the real air temperature or make inanimate objects like car parts or radiators cool any faster than the air temperature alone would.
What's the difference between wind chill and heat index?
Wind chill estimates how much colder moving air makes you feel in cold weather; heat index estimates how much hotter high humidity makes you feel in warm weather — different formulas, opposite temperature ranges.
What is the wind chill at 20°F with a 10 mph wind?
About 8.9°F (-12.8°C) — reused from this calculator's example table.
Example wind chill calculations
| Temperature | Wind speed | Wind chill |
|---|
| 30°F | 20 mph | 17.4°F |
| 20°F | 10 mph | 8.9°F |
| 0°F | 15 mph | -19.4°F |
| -10°F | 25 mph | -37.5°F |
| 40°F | 5 mph | 36.5°F |
Frequently asked questions
Why doesn't wind chill apply above 50°F?
The NOAA formula was derived from how quickly the human face loses heat in cold, windy conditions. Above 50°F the body does not lose heat the same way, so the formula's assumptions no longer hold and NOAA does not publish wind chill values for warmer temperatures.
Why is a minimum wind speed of 3 mph required?
At very low wind speeds the formula becomes unstable and can produce a 'feels like' value warmer than the actual air temperature, which is not physically meaningful. NOAA sets 3 mph as the minimum for the formula to apply.
Does wind chill affect how fast water freezes or car engines cool?
No. Wind chill only describes how cold exposed human skin feels — it does not change the actual air temperature, and it does not make inanimate objects like car parts, pipes, or car radiators cool faster than the air temperature alone would.
How is wind chill different from the heat index?
Wind chill estimates how much colder moving air makes you feel in cold weather. The heat index estimates how much hotter high humidity makes you feel in warm weather. They use different formulas and apply in opposite temperature ranges.
This calculator uses the official NOAA/NWS wind chill formula, valid only for air temperature at or below 50°F (10°C) and wind speed at or above 3 mph (5 km/h). Individual cold tolerance, clothing, sun exposure, and humidity are not accounted for, so treat the result as a general reference rather than a precise medical threshold.
Sources: NOAA/NWS Wind Chill