Wind Chill Calculator
How cold does it really feel out there? Set the temperature and wind speed to get the official NWS wind chill — the feels-like temperature on exposed skin — plus how fast frostbite can set in and a full wind chill chart for planning ahead.
10°F with a 20 mph wind feels like
-9°F
Wind chill (NWS 2001 formula) = -22.7°C
⚠️ Frostbite possible with prolonged exposure
Frostbite is possible on prolonged exposure. Dress in layers and keep skin covered.
Wind chill chart (°F, wind in mph)
| Wind ↓ / Temp → | 40°F | 30°F | 20°F | 10°F | 0°F | -10°F | -20°F | -30°F |
|---|---|---|---|---|---|---|---|---|
| 5 mph | 36° | 25° | 13° | 1° | -11° | -22° | -34° | -46° |
| 10 mph | 34° | 21° | 9° | -4° | -16° | -28° | -41° | -53° |
| 15 mph | 32° | 19° | 6° | -7° | -19° | -32° | -45° | -58° |
| 20 mph | 30° | 17° | 4° | -9° | -22° | -35° | -48° | -61° |
| 25 mph | 29° | 16° | 3° | -11° | -24° | -37° | -51° | -64° |
| 30 mph | 28° | 15° | 1° | -12° | -26° | -39° | -53° | -67° |
| 35 mph | 28° | 14° | 0° | -14° | -27° | -41° | -55° | -69° |
| 40 mph | 27° | 13° | -1° | -15° | -29° | -43° | -57° | -71° |
Shading shows frostbite time on exposed skin: orange ≈ 30 min, light red ≈ 10 min, red ≈ 5 min.
The NWS wind chill formula
The calculator uses the formula adopted by the US National Weather Service and Environment Canada in November 2001:
WC (°F) = 35.74 + 0.6215·T − 35.75·V0.16 + 0.4275·T·V0.16
where T is the air temperature in °F and V is the wind speed in mph. Unlike the 1945 original, which measured how fast water froze in a plastic cylinder, the 2001 revision models heat loss from a human face — the body part usually left exposed in winter. Scientists computed how wind accelerates heat transfer from skin at face level (about 5 feet), assumed a walking speed of 3 mph, and calibrated the model against clinical trials in which volunteers with temperature sensors on their faces walked on treadmills in a refrigerated wind tunnel.
Worked example
Say it is 5°F with a 30 mph wind. First, V0.16 = 300.16 ≈ 1.723. Then: WC = 35.74 + 0.6215 × 5 − 35.75 × 1.723 + 0.4275 × 5 × 1.723 = 35.74 + 3.11 − 61.61 + 3.68 ≈ −19°F. Air that reads 5°F on the thermometer feels like −19°F on your skin — cold enough for frostbite on exposed skin in about 30 minutes.
More weather tools
Wind chill covers the cold half of the year. In summer, the heat index calculator does the opposite job — it tells you how much hotter humid air feels — and the dew point calculator shows how muggy the air actually is. Need to switch between Fahrenheit and Celsius? Use the temperature converter.