Wind Chill Calculator
Enter the air temperature and wind speed to find the wind chill temperature — how cold it really feels on exposed skin — plus a frostbite risk estimate. Supports °C/°F and km/h, mph or m/s.
Find How Cold It Really Feels
Wind Chill Formula
Where:
- \(T_{wc}\) — wind chill temperature, the perceived temperature in °C
- \(T\) — air temperature in °C
- \(V\) — wind speed in km/h, measured 10 m above the ground
This is the joint Environment Canada and US National Weather Service formula adopted in 2001. It combines temperature and wind speed into a single "feels like" value that estimates how quickly exposed skin loses heat. The fractional exponent \(V^{0.16}\) reflects the fact that the cooling effect of wind rises steeply at first, then levels off as the wind gets stronger.
Wind Chill – Calculation Example
Example: the air temperature is \(-5\) °C and the wind blows at 20 km/h — a typical cold winter day. How cold does it feel?
\[ V^{0.16} = 20^{0.16} \approx 1.6150 \]
\[ T_{wc} = 13.12 + 0.6215 \cdot (-5) - 11.37 \cdot 1.6150 + 0.3965 \cdot (-5) \cdot 1.6150 \]
\[ T_{wc} = 13.12 - 3.108 - 18.363 - 3.202 \approx -11.55\ \text{°C} \]
Result: it feels like about \(-11.6\) °C (11.2 °F) — roughly 6.5 °C colder than the thermometer reads. At this level, exposed skin may feel cold and uncomfortable, so cover up.
How to use the calculator
- Enter the Air temperature (T) and choose the unit — °C or °F.
- Enter the Wind speed (V) and select its unit: km/h, mph or m/s. Use the speed measured or forecast at the standard 10 m height (a normal weather-report value).
- Read the Wind chill temperature — the "feels like" value in both °C and °F, together with the difference from the actual air temperature and a frostbite risk assessment.
- Check the details panel below the result: it shows the formula applied to your numbers and flags any validity issues (see the notes below).
What is wind chill and why it matters
Wind chill is not a different temperature in the air — it is a measure of how fast your body loses heat. In calm conditions, your skin warms a thin cushion of air around it. Wind strips this layer away, so heat is carried off faster, and the colder it feels. The wind chill temperature answers the question: "at this temperature and wind, how cold does it feel equivalent to on a calm day?" A \(-5\) °C day with a 20 km/h wind feels to your skin like a calm day at about \(-11.6\) °C.
The practical importance is frostbite and hypothermia prevention. The result panel includes a risk category based on the US National Weather Service wind chill scale. For example, a wind chill between \(-28\) and \(-39\) °C means frostbite is possible on exposed skin in 10 to 30 minutes; below \(-48\) °C the window shrinks to 5 to 10 minutes. Schools, outdoor workers and event organizers often use these thresholds to decide whether activities should be cancelled or shortened.
Two things worth remembering when interpreting the result. First, wind chill applies to exposed skin, not to a person dressed properly or to inanimate objects — a car engine or water pipe cools only to the actual air temperature, no faster. Second, the calculation assumes cloudy or shaded conditions: bright sunshine can raise the perceived temperature by roughly 10 °C (18 °F), so a sunny \(-5\) °C day with wind may feel noticeably milder than the calculator indicates.
Assumptions, limitations and tips
- Valid temperature range: the formula is calibrated for air temperatures of 10 °C (50 °F) and below. Above that it is not meaningful — in warm weather, use heat-index style measures instead.
- Valid wind range: the formula applies to wind speeds above 4.8 km/h (3 mph / 1.3 m/s). Below this threshold, the calculator takes the wind chill to equal the air temperature, since light wind barely increases heat loss.
- Anemometer height: wind speed should be the standard value measured 10 m above the ground. Wind at street level between buildings can be stronger or gustier than the reported value.
- Individual factors: the result models an average adult face walking into the wind. Age, fitness, clothing, body fat and whether you are sweating all shift your personal comfort and risk.
- Unit conversions: the calculator converts °F, mph and m/s internally. If you need to check or convert speeds yourself for other purposes, the speed unit converter handles km/h, mph, m/s and more; the fuel economy converter covers related mph-based unit conversions.
Reference: frostbite risk by wind chill
| Wind chill (°C) | Risk level and guidance |
|---|---|
| 0 to −9 | Low risk — dress warmly, no unusual protection needed |
| −10 to −27 | Slight risk — exposed skin may feel cold and uncomfortable; cover up |
| −28 to −39 | Increasing risk — frostbite possible in 10 to 30 minutes on exposed skin |
| −40 to −48 | High risk — frostbite possible in 5 to 10 minutes |
| −49 to −55 | Very high risk — frostbite possible in 2 to 5 minutes |
| Below −55 | Extreme risk — frostbite possible in under 2 minutes; avoid exposure |
Whenever the risk reaches the "increasing" level or worse, limit time outdoors, keep skin covered, and watch companions — especially children and older adults — for signs of numbness or waxy, pale skin, which are early frostbite warning signs.
Frequently Asked Questions
How do I calculate wind chill by hand in Fahrenheit and mph?
The US National Weather Service imperial version is \( T_{wc} = 35.74 + 0.6215\,T - 35.75\,V^{0.16} + 0.3965\,T\,V^{0.16} \), where \(T\) is in °F and \(V\) is in mph. Compute \(V^{0.16}\) first (a calculator with an exponent key, e.g. \(x^y\), makes this easy), then substitute and add up the four terms. The result is always lower than the actual air temperature once wind exceeds 3 mph.
Does wind chill affect cars, pipes, or other objects?
No. Wind chill describes how fast living skin loses heat, because wind strips away the warm boundary layer your body creates. An inanimate object can never be cooled below the true air temperature no matter how hard the wind blows — it just reaches that temperature faster. So a car's engine, water pipes, or fuel lines are governed by the actual thermometer reading, not the feels-like value.
Should I enter sustained wind speed or gusts?
Use the sustained (average) wind speed from a standard weather report, which is typically averaged over a minute or two at 10 m height. The official formula was calibrated with these values, not gusts. Entering gust speeds overstates the wind chill. If only a gust figure is available, expect the real wind chill to be somewhat milder than your result, since gusts last only seconds.
Why doesn't the calculator work above 10 °C (50 °F)?
The 2001 formula was derived from experiments on how fast a human face cools in cold conditions; above 10 °C the mathematical result stops matching reality. In warm weather, wind generally helps you feel cooler by evaporating sweat, which is the opposite mechanism. For hot, humid conditions the relevant measure is the heat index, and for hot, dry, windy weather it is simply the air temperature plus evaporative cooling.
What wind chill temperature is considered dangerous?
As a rule of thumb, frostbite risk becomes meaningful below about −27 °C (−18 °F), where exposed skin can freeze in around 30 minutes. Below −48 °C (−55 °F) the window shrinks to under 10 minutes. School districts and employers commonly cancel or shorten outdoor activities at these levels. If you must be out, cover all exposed skin, layer up, and check your companions regularly — numbness or waxy, pale skin are early frostbite signs that need immediate warming and, if persistent, medical attention.
What are the most common mistakes when computing wind chill?
The biggest one is mixing units: the metric formula needs km/h, so entering a mph value directly makes the result far too mild (multiply mph by 1.609 first). Other frequent errors are using wind measured at street level instead of the 10 m standard, applying the formula above 10 °C where it has no meaning, and forgetting that sunshine can raise the felt temperature by roughly 10 °C on a bright day.
Does humidity or my clothing change the wind chill value?
Humidity plays almost no role in the official wind chill formula — it is based purely on temperature and wind speed, and moisture's effect on cold-weather heat loss is minor. Clothing does not change the number, but it changes your risk: the value applies to exposed skin only. Dressed properly with windproof outer layers, you experience something much closer to the actual air temperature than to the wind chill.