Find the feels-like temperature and frostbite risk from air temperature and wind speed using the NWS Wind Chill Index formula. Works in °F or °C and mph or kph.
Wind chill is the perceived temperature felt on exposed skin on a cold, windy day — colder than what your thermometer reads because wind strips the warm air layer next to your skin. The National Weather Service publishes a Wind Chill Index (revised 2001) that combines air temperature and wind speed into a single feels-like number. Wind chill matters for outdoor safety: it tells you when frostbite becomes a real risk and how long you can safely stay outside. The calculator below applies the NWS formula and shows the frostbite risk level for your conditions.
The actual air temperature measured by a thermometer.
Sustained wind speed at 10 m elevation (NWS standard).
Feels-like temperature:6.2°F
Actual air temperature: 20.0°F · Wind makes it feel 13.8°F colder
Formula: Wind Chill (°F) = 35.74 + 0.6215·T − 35.75·V^0.16 + 0.4275·T·V^0.16 (NWS Wind Chill Index, 2001 revision). Valid for T ≤ 50°F and V ≥ 3 mph.
| Wind (mph) | Feels like (°F) | Difference |
|---|---|---|
| 5 | 13.0°F | 7°F colder |
| 10 | 8.9°F | 11°F colder |
| 15 | 6.2°F | 14°F colder |
| 20 | 4.2°F | 16°F colder |
| 25 | 2.6°F | 17°F colder |
| 30 | 1.3°F | 19°F colder |
| 35 | 0.1°F | 20°F colder |
| 40 | -0.9°F | 21°F colder |
A 20°F day already feels cold, but a 30 mph wind makes it feel like about 3°F — well into frostbite territory. Cover exposed skin before extended time outdoors.
Cross-checked against authoritative formulas (IRS, NIST, ACM) and updated for 2025/2026 tax years and rates.
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A wind chill calculator is a free tool that estimates the feels-like temperature your body actually experiences on cold, windy days. Our wind chill calculator uses the NWS Wind Chill Index (revised 2001), the same formula used by the National Weather Service for winter advisories. The wind chill calculator also shows the frostbite risk level so you know how to dress and how long to stay outside.
How it works
Our wind chill calculator finds the feels-like temperature and frostbite risk from air temperature and wind speed using the NWS Wind Chill Index formula (revised 2001), in three steps.
Type the actual air temperature in °F or °C. The wind chill calculator uses this as T in the NWS formula, converting to °F internally if needed. Valid only when T ≤ 50°F (10°C); above that, wind chill is not meaningful.
Type the sustained wind speed in mph or kph. The wind chill calculator converts to mph internally if needed. Valid only when V ≥ 3 mph (4.8 kph). Use the anemometer value if you have one, or the public forecast wind speed.
The wind chill calculator shows the feels-like temperature, how much colder the wind makes it feel, and a frostbite risk level (Low, Moderate, High, or Very High) with the approximate time to frostbite on exposed skin. A reference table below shows feels-like values at common wind speeds.