Wind Chill Calculator
Calculate the real feels-like temperature in cold weather using the official National Weather Service formula. Enter air temperature and wind speed — get wind chill and frostbite risk instantly. Supports °F/°C and mph/km/h.
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Wind Chill Calculator
NWS IAQ/TI Formula (2001)
20°
Actual Temp
6°
Feels Like — Wind Chill
SAFETY REFERENCE
Wind Chill Frostbite Risk Chart
Official NWS frostbite-risk levels and estimated times to frostbite on exposed skin.
| Wind Chill (°F) | Wind Chill (°C) | Risk Level | Frostbite Time | Action |
|---|---|---|---|---|
| Above 32°F | Above 0°C | Safe | No risk | Normal outdoor activity |
| 32°F to 0°F | 0°C to -18°C | Caution | Low risk | Dress warmly, cover extremities |
| -1°F to -19°F | -18°C to -28°C | Danger | 30 min or less | Limit outdoor exposure, cover all skin |
| -20°F to -39°F | -29°C to -39°C | High Danger | 10-30 minutes | Minimize outdoor time, buddy system |
| -40°F to -69°F | -40°C to -56°C | Extreme | 5-10 minutes | Avoid outdoors, only with full protection |
| -70°F and below | -57°C and below | Life-Threatening | Under 2 minutes | Do NOT go outside |
REFERENCE CHART
Wind Chill Chart (°F)
Air temp in columns, wind speed in rows. Color = frostbite risk in 30 min or less.
| mph / °F | 35 | 30 | 25 | 20 | 15 | 10 | 5 | 0 | -5 | -10 | -15 | -20 | -25 | -30 | -35 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 5 mph | 31 | 25 | 19 | 13 | 7 | 1 | -5 | -11 | -16 | -22 | -28 | -34 | -40 | -46 | -52 |
| 10 mph | 27 | 21 | 15 | 9 | 3 | -4 | -10 | -16 | -22 | -28 | -35 | -41 | -47 | -53 | -59 |
| 15 mph | 25 | 19 | 13 | 6 | 0 | -7 | -13 | -19 | -26 | -32 | -39 | -45 | -51 | -58 | -64 |
| 20 mph | 24 | 17 | 11 | 4 | -2 | -9 | -15 | -22 | -29 | -35 | -42 | -48 | -55 | -61 | -68 |
| 25 mph | 23 | 16 | 9 | 3 | -4 | -11 | -17 | -24 | -31 | -37 | -44 | -51 | -58 | -64 | -71 |
| 30 mph | 22 | 15 | 8 | 1 | -5 | -12 | -19 | -26 | -33 | -39 | -46 | -53 | -60 | -67 | -73 |
| 35 mph | 21 | 14 | 7 | 0 | -7 | -14 | -21 | -27 | -34 | -41 | -48 | -55 | -62 | -69 | -76 |
| 40 mph | 20 | 13 | 6 | -1 | -8 | -15 | -22 | -29 | -36 | -43 | -50 | -57 | -64 | -71 | -78 |
| 45 mph | 19 | 12 | 5 | -2 | -9 | -16 | -23 | -30 | -37 | -44 | -51 | -58 | -65 | -72 | -79 |
| 50 mph | 19 | 12 | 4 | -3 | -10 | -17 | -24 | -31 | -38 | -45 | -52 | -60 | -67 | -74 | -81 |
| 55 mph | 18 | 11 | 4 | -3 | -11 | -18 | -25 | -32 | -39 | -46 | -54 | -61 | -68 | -75 | -82 |
| 60 mph | 17 | 10 | 3 | -4 | -11 | -19 | -26 | -33 | -40 | -48 | -55 | -62 | -69 | -76 | -84 |
Air temp in columns, wind speed in rows. Values computed live from the NWS formula (32°F = 0°C). Shaded by risk tier — see the frostbite chart above.
❄️ Wind Chill Doesn't Lower Air Temperature
A thermometer left outside still reads the true air temperature. Wind chill only describes how quickly exposed skin — or any object above ambient temperature — loses heat to moving air. It doesn't make water freeze faster or change any physical property of the air itself.
🧊 Frostbite vs Hypothermia
Frostbite affects extremities — fingers, toes, nose, ears, and cheeks. Early signs are numbness, tingling, and white or grayish-yellow skin. Severe frostbite can cause permanent tissue loss.
Hypothermia occurs when core body temperature drops below 95°F (35°C). Signs include intense shivering, confusion, slurred speech, and loss of coordination. Both are medical emergencies — seek warm shelter and medical help immediately.
🧥 Cold Weather Layering Guide
- Base layer: moisture-wicking synthetic or wool to pull sweat away from skin — avoid cotton, it stays wet and accelerates heat loss
- Mid layer: insulating fleece or down to trap warm air
- Outer layer: windproof and waterproof to block wind and precipitation — in dangerous wind chill, this layer is critical, since a windbreaker alone can dramatically reduce the feels-like drop
How Wind Chill Is Calculated
The wind chill index used today was developed jointly by the US National Weather Service and the Meteorological Service of Canada, and adopted in November 2001. It was validated using human subjects walking outdoors at 5 feet (1.5m) — typical face height — at a controlled wind speed and air temperature, replacing an older, less accurate formula from the 1940s.
The NWS Wind Chill Formula (°F / mph)
Wind Chill (°F) = 35.74 + 0.6215T − 35.75(V^0.16) + 0.4275T(V^0.16)Example: T = 20°F, V = 15 mph → 35.74 + 0.6215(20) − 35.75(15^0.16) + 0.4275(20)(15^0.16) ≈ 6°F feels like.
The Formula in °C / km/h
Wind Chill (°C) = 13.12 + 0.6215T − 11.37(V^0.16) + 0.3965T(V^0.16)When the formula applies: only at air temperatures of 50°F (10°C) or below, with wind speed above 3 mph (5 km/h). Above that, or in calm wind, the relevant "feels like" metric is instead the Heat Index, which accounts for humidity — try our Heat Index Calculator.
Wind Chill, Frostbite & Cold Weather Safety
How Wind Accelerates Heat Loss
Your body maintains a thin layer of warm air next to your skin. In calm conditions this insulating layer is relatively stable. Wind disrupts and removes this warm air, forcing your body to work harder to maintain skin temperature — the faster the wind, the faster this protective layer is stripped away and the colder skin feels.
Why Higher Wind Speeds Have Diminishing Returns
Going from calm air to a 10 mph breeze on a 20°F day drops the wind chill by roughly 17°F. But going from 40 mph to 50 mph drops it only 1-2°F more. Once the insulating air layer around your skin is fully stripped away, additional wind speed has a much smaller effect, since skin is already losing heat at close to the maximum rate.
Frostbite: Stages and Warning Signs
Frostnip is the mildest form — skin turns red and feels cold and numb, but no tissue damage occurs and warming quickly reverses it. Superficial frostbite freezes the outer skin layers — skin appears white or grey, feels hard on the surface but soft underneath. Deep frostbite penetrates deeper tissue and can cause permanent damage or amputation. All exposed skin should be covered once wind chill reaches -19°F (-28°C) or below.
— FAQ