Wind Chill Calculator
Enter temperature and wind speed on the left, and the wind chill, the difference from actual temperature, and the feels-like category appear on the right.
Input
Enter an air temperature and wind speed to see the wind chill calculated automatically.
Result
- Air temperature
- —
- Feels-like category
- —
- Wind-driven drop
- —
- Standard formula range
- —
Wind chill is an estimate from the standard NWS wind chill formula (°F, mph). Sunshine, humidity, clothing, wetness, and personal health are not part of the formula, so treat this as a reference when deciding what to wear or how long to stay outside.
ready to use.
- Visible firstKeep the input and result positions clear.
- Results firstPut the main number up front and keep the process secondary.
- Less to askNo sign-up or extra information before using the tool.
How to Read Wind Chill: The NWS Feels-Like Temperature, Explained
Wind chill measures how much colder your skin feels when wind strips heat away faster than still air would at the same air temperature. On a calm day, 10°F is uncomfortable but manageable; add a 20 mph wind and exposed skin loses heat as if the air were nearly -9°F — that gap is exactly what a Wind Chill Advisory or Warning is built to warn you about.
The number this calculator shows is not the actual air temperature — a thermometer outside would still read the value you entered. It is a standardized estimate from the National Weather Service (NWS) wind chill formula, using °F and mph. Sunshine, humidity, clothing, and personal health aren’t inputs to the formula, so use the result as guidance, not a guarantee.
Wind chill is a cold-weather danger index, not just a number
Wind chill (feels-like temperature) captures how much faster exposed skin loses heat when wind is added to a given air temperature. It matters most for anyone heading outside in winter — commuting, shoveling, running, skiing, or working outdoors — because judging risk from air temperature alone misses how wind changes frostbite and hypothermia timelines.
How to use the calculator
Fill in the two fields on the left and the result on the right updates instantly — there’s no calculate button to press.
- Enter air temperature in Fahrenheit (°F). Use a minus sign for sub-zero readings.
- Enter wind speed in miles per hour (mph). If your forecast gives knots or km/h, convert to mph first (1 knot ≈ 1.15 mph; 1 km/h ≈ 0.62 mph).
- Use the preset chips (Breezy, Freezing point, Cold snap, Arctic blast, Extreme cold) to load common winter scenarios instantly.
- Read the wind chill together with the difference from actual temperature and the feels-like category — not the wind chill number alone.
The two inputs, their ranges, and the low-wind cutoff
Both values are required for a wind chill to be calculated. Leaving either field empty keeps the result in a neutral, unfilled state.
- Air temperature: actual outdoor air temperature (°F). Accepted range is -60°F to 130°F.
- Wind speed: sustained wind speed near the surface (mph). Accepted range is 0 to 120 mph.
- The NWS formula applies to air temperature at or below 50°F combined with wind above 3 mph.
- Below 3 mph, wind has essentially no cooling effect, so wind chill is shown as equal to the air temperature.
The NWS wind chill formula
This calculator uses the exact formula adopted by the U.S. and Canadian weather services in 2001, using air temperature T in °F and wind speed V in mph.
- Wind chill (°F) = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275 × T × V^0.16
- T = air temperature in °F, V = wind speed in mph
- Below 3 mph: wind chill = T (no wind adjustment applied)
- The result is rounded to the nearest whole degree Fahrenheit.
Worked example: 10°F with 20 mph wind
The Cold snap preset loads an air temperature of 10°F and a wind speed of 20 mph. Plugging those into the NWS formula gives a wind chill of about -9°F — 19 degrees colder than the actual air temperature, landing in the Very cold category where frostbite is possible on exposed skin in about 30 minutes. The thermometer still reads 10°F; the -9°F describes how fast your skin loses heat, as if the air itself were that cold.
- Air temperature
- 10°F
- Wind speed
- 20 mph
- Wind chill
- -9°F
- Difference from air temp
- -19°F
- Feel
- Very cold
Reading the four results together
Looking at all four values at once gives you a much clearer read on outdoor risk than the wind chill number alone.
- Wind chill: the feels-like temperature that accounts for how wind accelerates heat loss from skin.
- Difference from air temperature: how many degrees colder the wind is making it feel (usually negative).
- Feels-like category: a plain-language label — Comfortable, Chilly, Cold, Very cold, or Danger.
- Standard formula range: shown as "Within standard range" when temperature is 50°F or below and wind exceeds 3 mph, otherwise "Reference value (outside range)".
Feels-like category thresholds (°F)
These bands translate the calculated wind chill into the same plain-language categories the tool displays, matching NWS guidance on cold-weather risk.
- 50°F and above: Comfortable
- 32°F to 50°F: Chilly
- 14°F to 32°F: Cold
- -13°F to 14°F: Very cold (frostbite risk)
- Below -13°F: Danger (frostbite possible in minutes)
Outside the standard range: treat results as reference only
The NWS wind chill formula was built and validated for air temperature at or below 50°F with wind above 3 mph. Above 50°F, the heat index — not wind chill — governs how heat and humidity feel, and calm cold air (under 3 mph) is best judged by the actual temperature itself. This calculator will still compute a number outside that range, but it’s labeled "Reference value (outside range)" so you don’t mistake it for an official reading.
Common mistakes to avoid
A few misreadings account for most wind chill confusion — worth checking before you head out.
- Wind-unit mix-ups: entering a knots or km/h value directly into the mph field understates or overstates wind chill. Convert first — 1 knot ≈ 1.15 mph, 1 km/h ≈ 0.62 mph.
- Using wind chill in warm weather: above 50°F, look at the heat index instead — wind chill isn’t designed for that range.
- Entering gusts instead of sustained wind: unless you’re on an exposed ridge, coast, or bridge, sustained wind speed is the more representative input.
- Confusing wind chill with actual temperature: the thermometer doesn’t change — wind chill describes how fast exposed skin loses heat, not a new air temperature.
Pre-departure checklist for cold, windy days
Pair the calculated wind chill with these checks before heading outside.
- If the category is "Very cold" or "Danger," limit exposed skin time and layer up with wind-resistant outer gear.
- Wet clothing or sweat dramatically speeds heat loss — stay dry and change out of damp layers quickly.
- Children, older adults, and anyone with circulatory or chronic conditions face higher risk at the same wind chill.
- Always defer to an active NWS Wind Chill Advisory or Warning over this calculator’s output — official alerts factor in local conditions this tool doesn’t.
Wind Chill Calculator: Frequently Asked Questions
Why does wind chill equal the air temperature when wind is below 3 mph?
At very low wind speeds, air near the skin doesn’t get replaced fast enough to meaningfully speed up heat loss beyond what still air already does. Below 3 mph the NWS formula treats wind effect as negligible, so the calculator displays wind chill equal to the actual air temperature.
Does the calculator still work if the air temperature is above 50°F?
You can enter a value above 50°F, but the result is flagged "Reference value (outside range)" because the NWS wind chill formula was built for cold-weather conditions. For warm, humid weather, the heat index is the appropriate feels-like measure instead.
Does a wind chill of -9°F mean the actual temperature dropped that low?
No. The air temperature is still whatever you entered — 10°F in the worked example. -9°F describes how quickly exposed skin loses heat in that wind, as though the air itself were -9°F, not an actual drop in the thermometer reading.
My forecast gives wind speed in knots — how do I convert it?
This calculator uses mph. Multiply knots by about 1.15 to get mph (for example, 17 knots ≈ 20 mph). For km/h, multiply by 0.62 (for example, 32 km/h ≈ 20 mph).
Should I use sustained wind or wind gusts?
For everyday planning, sustained wind speed gives the more representative wind chill. If you’ll be on an exposed ridge, open coastline, or bridge where gusts are frequent and sudden, it’s worth also checking the result using the higher gust speed.
Do sunshine, humidity, or clothing affect the calculated wind chill?
No — the formula only uses air temperature and wind speed. Direct sunshine can make it feel less cold than the calculated value, while wet clothing, low body fat, or poor circulation can make actual risk higher than the number suggests, so treat the result as a planning reference, not a precise measurement.
Reference checked: 2026-07-16. Uses the standard NWS wind chill formula (°F, mph); wind chill is an estimate for planning purposes.