Calculate the "feels like" temperature using the NWS wind chill formula — valid for temperatures at or below 50°F and wind speeds above 3 mph.
| Temp \ Wind | 5 mph | 10 mph | 15 mph | 20 mph | 30 mph | 40 mph |
|---|---|---|---|---|---|---|
| 40°F | 36 | 34 | 32 | 30 | 28 | 27 |
| 30°F | 25 | 21 | 19 | 17 | 15 | 13 |
| 20°F | 13 | 9 | 6 | 4 | 1 | -1 |
| 10°F | 1 | -4 | -7 | -9 | -12 | -15 |
| 0°F | -11 | -16 | -19 | -22 | -26 | -29 |
| -10°F | -22 | -28 | -32 | -35 | -39 | -43 |
| -20°F | -34 | -41 | -45 | -48 | -53 | -57 |
| -30°F | -46 | -53 | -58 | -61 | -67 | -71 |
| > 32°F | Cool |
| 0–32°F | Cold |
| -20–0°F | Very Cold |
| -40 to -20°F | Bitter Cold |
| -60 to -40°F | Extreme Cold |
| < -60°F | Dangerous / Frostbite |
What does 20°F feel like with a 20 mph wind? The NWS wind chill formula says 4.2°F, almost 16 degrees colder than the thermometer. You can enter the air temperature in °F or °C and the wind in mph, km/h or m/s, and this page returns the wind chill in both temperature scales, a condition label and a rough frostbite-time band.
The formula is WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275·T·V^0.16, with T in °F and V in mph. It is the 2001 NWS and Meteorological Service of Canada formula, valid for air temperatures at or below 50°F and wind above about 3 mph. The page converts °C to °F, km/h × 0.621371 and m/s × 2.23694 to mph, and shows 'Outside formula range' otherwise.
What changes if one input moves? From 20°F, wind at 10 mph gives 8.9°F, at 20 mph gives 4.2°F, at 30 mph gives 1.3°F. Wind has diminishing returns because of the 0.16 exponent: doubling from 10 to 20 mph costs 4.6 degrees. Temperature is steadier. At 20 mph, 25°F gives 10.8°F, 20°F gives 4.2°F, 15°F gives −2.3°F and 10°F gives −8.9°F, so every 5°F colder air lowers the wind chill by about 6.6.
Worked example: 20°F and 20 mph. 20^0.16 = 1.6150. Then 35.74 + 0.6215 × 20 − 35.75 × 1.6150 + 0.4275 × 20 × 1.6150 = 35.74 + 12.43 − 57.74 + 13.81 = 4.24. The page shows 4.2°F, or −15.4°C, rounded to one decimal. Its label for this is Cold. Its frostbite column says 'No risk' for any wind chill above 0°F, which is a coarse banding and not a guarantee.
The formula is only valid at or below 50°F and for wind of about 3 mph or more. At 55°F or in a 2 mph breeze there is no wind chill to speak of, and the page returns no value.
No. Wind chill describes heat loss from exposed human skin. Inanimate objects only cool to the air temperature, and wind helps them reach it sooner but never takes them below it.
A human face, walking at about 3 mph, with wind measured at the standard 10 m height and adjusted down to face level, and no sunshine. Sun, wet clothing and shelter all change what you feel.
As a rough guide only. The thresholds are simplified bands keyed to the wind chill value. Use the official NWS wind chill chart and local warnings for decisions, and take extra care with children, older adults and anyone with circulation problems. This is not medical advice.
The result shifts a lot. At 20°F, 20 mph gives 4.2°F, but 20 km/h (12.4 mph) gives 7.5°F. Check the unit menu before reading the answer.