The Boundary Layer
Your body warms a thin layer of air right next to your skin, a microscopic thermal blanket. Wind constantly replaces it with colder air, so you lose heat faster. The stronger the wind, the faster the loss.
Weather calculators
Wind Chill Calculator: NWS Formula & Frostbite Risk
Wind chill from temp and wind speed. NWS formula. Frostbite risk. °F, °C, K.
By Jeff Beem
Updated
01
Settings
02
Air temperature
03
Wind speed
Wind speed must be > 3 mph (4.8 km/h) for wind chill.
Results
Low Risk
No immediate frostbite threat.
Wind chill
33.1 °F
All units
°F33.1 °F
°C0.6 °C
K273.8 K
Information hub
Frostbite trend
Wind chill heatmap. Rows = wind speed (mph), columns = temperature (°F). Colors match risk levels.
| Wind → | 20°F | 0°F | -20°F |
|---|---|---|---|
| 10 mph | 9 | -16 | -41 |
| 30 mph | 1 | -26 | -53 |
| 50 mph | -3 | -31 | -60 |
Low ~30 min ~10 min ~5 min
Frostbite vs hypothermia
Frostbite
Occurs when skin and tissue actually freeze. Usually starts with extremities: fingers, toes, nose, ears.
Hypothermia
A drop in core body temperature below 95°F (35°C). A systemic failure that can happen even before skin freezes.
Wind Chill: How Cold It Really Feels
Wind chill tells you how cold it feels when wind strips the warm air layer next to your skin. Developed jointly by the National Weather Service and Environment Canada, the formula converts temperature and wind speed into a single "feels like" value for exposed skin.
Core Concepts
The Physics Limit
Wind chill cannot cool anything below air temperature. It only affects how quickly you reach that temp. Cars, pipes, and objects will not go below the thermometer reading, only humans feel colder because we're trying to stay at 98.6°F.
Frostbite vs Hypothermia
Frostbite = skin and tissue actually freeze, usually starting at fingers, toes, nose, ears. Hypothermia = core body temp drops below 95°F (35°C), a systemic failure that can happen before frostbite.
Valid Range
The formula applies only when T ≤ 50°F and wind > 3 mph. It's based on a human face model at 5 feet, clear night, no sun. Outside that range, use the actual temperature.
Wind Chill Calculator: NWS Formula & Frostbite Risk
Find how cold it really feels from air temperature and wind speed. NWS/Environment Canada formula. Frostbite time estimates (5, 10, 30 min). Free wind chill calculator.
What This Calculator Does
The Wind Chill Calculator computes the "feels like" temperature when cold air and wind combine to strip heat from exposed skin. It uses the official NWS/Environment Canada wind chill formula adopted in 2001 and displays frostbite risk levels (low, moderate, high, or extreme) with estimated time-to-frostbite. Enter an air temperature and wind speed to see how cold it really feels outside. The formula applies only when air temperature is at or below 50 °F (10 °C) and wind speed exceeds 3 mph (4.8 km/h), outside that range, the calculator indicates the model does not apply.
- Inputs:Air temperature (°F or °C) and wind speed (mph or km/h).
- Outputs:Wind chill temperature, frostbite risk level, and estimated time to frostbite on exposed skin.
How Wind Chill Works
Wind chill is the apparent temperature when wind blows across exposed skin, the "feels like" reading that reflects heat loss rate. The NWS/Environment Canada formula: with T in °F and v in mph. Wind removes the warm boundary layer next to your skin, increasing heat loss. The index assumes a human face model at 5 feet, clear night, no sun.
How to Use This Calculator
Find the wind chill and frostbite risk in three quick steps:
- Enter Air Temperature:Type the current air temperature in °F or °C. The NWS formula applies when the temperature is at or below 50 °F (10 °C). Above that threshold, wind chill is not meaningful.
- Enter Wind Speed:Type the wind speed in mph or km/h. The formula requires wind above 3 mph (4.8 km/h). In calm conditions, the actual temperature is your "feels like" temperature.
- Read the Results:The calculator displays the wind chill temperature, a frostbite risk level (low, moderate, high, or extreme), and the estimated time to frostbite on exposed skin. If inputs fall outside the valid range, the tool shows a clear out-of-range message.
Formula Limits: When Wind Chill Applies
The formula applies only when air temperature is ≤ 50°F (10°C) and wind speed is > 3 mph (4.8 km/h). Warmer temps or calm air fall outside the model, use the actual temperature. The calculator flags out-of-range inputs.
Frostbite Time Estimates
At 0°F with 15 mph wind, wind chill is -19°F and exposed skin can freeze in about 30 minutes. Colder wind chills shorten the time: below -35°F, frostbite can occur in roughly 5 minutes. Hypothermia, a drop in core body temperature below 95°F, can develop before frostbite and is life-threatening.
Wind Chill vs Actual Temperature
Wind chill cannot lower an object below air temperature. It only affects how quickly you reach that temperature. If it's 35°F with a wind chill of 20°F, water pipes will not freeze, the air is still above 32°F. For humans, wind increases heat loss because we're trying to maintain 98.6°F; for inanimate objects, wind only speeds how fast they equilibrate to the ambient temperature.
Wind Chill Calculator FAQ
What is wind chill?
Wind chill is the "feels like" temperature when wind blows across exposed skin, how cold it actually feels, not the thermometer reading. The NWS/Environment Canada formula: where T is air temp (°F) and v is wind speed (mph). Wind strips the warm boundary layer from your skin, so you lose heat faster.
When does the wind chill formula apply?
Only when air temperature is ≤ 50°F (10°C) and wind speed is > 3 mph (4.8 km/h). Above 50°F or in calm air, the model doesn't apply, use the actual temperature instead. The calculator shows "Formula Out of Range" when inputs fall outside these limits.
Can wind chill freeze water pipes?
No. Wind chill cannot lower an object's temperature below the actual air temperature. If it's 35°F outside with a wind chill of 20°F, your pipes won't freeze, the air is still above 32°F. Wind chill affects how quickly you cool toward that temperature. For humans, that means faster heat loss; for inanimate objects, it only speeds how fast they reach air temp.
What do the frostbite risk levels mean?
NWS guidelines: Low (> 5°F wind chill) = no immediate threat. Moderate (-19°F to 5°F) = frostbite possible in ~30 min. High (-35°F to -20°F) = ~10 min. Extreme (< -35°F) = ~5 min, with high hypothermia risk. Hypothermia, a drop in core temp below 95°F, can develop before frostbite.
How is wind chill different from heat index?
Both are "feels like" measures. Wind chill combines cold air and wind to estimate how quickly you lose heat. Heat index combines heat and humidity to estimate how hot it feels when sweat can't evaporate. Both use NWS-developed formulas.
Mathematical Reference Note
Calculation Logic: This tool uses standard mathematical algorithms. While we strive for accuracy, errors in logic or user input can result in incorrect data.
Verification: Results should be cross-checked if used for important academic, professional, or personal calculations.
Standard Terms: This tool is provided free of charge and as-is. CalcRegistry provides no warranty regarding the accuracy or fitness of these results for your specific needs.
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