Wind chill index is designed to describe the cooling effect of the wind. In theory, a wind chill of -25°F feels just as cold as a temperature of -25°F with no wind. In reality, however, the wind chill table, while somewhat accurate, is not very precise and a wind chill with a different combination of wind speed and ambient temperature will not always feel the same. For example, a wind chill of -12°C (temperature of 4°C with 45 mph winds) will feel different than a wind chill of -12°C (temperature of -4°C with 10 mph winds).
Wind chill is not measured by instruments, it's only detectable by the feel of the wind on exposed flesh. A wind chill below freezing will not freeze water if the ambient temperature is above freezing. For example, 35°F temperature with a wind speed of 40 mph creates a wind chill of 3°F, perhaps uncomfortable but it will not cause frostbite since the actual temperature is above freezing. Wind chill will cool outside objects faster, but will not cause them to cool to below the actual temperature. In the example just given, objects placed into an environment of 35°F with a 40mph wind will cool just as quickly as if they are put into an environment with a temperature of 3°F, but will not cool below the actual temperature of 35°F.
Color code:
| Comfortable to mildly unpleasant. |
| Unpleasant. |
| Frostbite possible. |
| Frostbite likely. Outdoor activity becomes dangerous. |
| Exposed flesh will freeze in about 30 seconds for the average person. |
| 5 mph 8 km/h |
10 mph 16 km/h |
15 mph 24 km/h |
20 mph 32 km/h |
25 mph 40 km/h |
30 mph 48 km/h |
35 mph 56 km/h |
40 mph 64 km/h |
45 mph 72 km/h |
|
|---|---|---|---|---|---|---|---|---|---|
| 45°F 7°C |
43°F 6°C |
34°F 1°C |
29°F -2°C |
26°F -3°C |
23°F -5°C |
21°F -6°C |
20°F -7°C |
19°F -7°C |
18°F -8°C |
| 40°F 4°C |
37°F 3°C |
28°F -2°C |
23°F -5°C |
19°F -7°C |
16°F -9°C |
13°F -11°C |
12°F -11°C |
11°F -12°C |
10°F -12°C |
| 35°F 2°C |
32°F 0°C |
22°F -6°C |
16°F -9°C |
12°F -11°C |
8°F -13°C |
6°F -14°C |
4°F -16°C |
3°F -16°C |
2°F -17°C |
| 30°F -1°C |
27°F -14°C |
16°F -9°C |
9°F -13°C |
4°F -16°C |
1°F -17°C |
-2°F -19°C |
-4°F -20°C |
-5°F -21°C |
-6°F -21°C |
| 25°F -4°C |
22°F -6°C |
10°F -12°C |
2°F -17°C |
-3°F -19°C |
-7°F -22°C |
-10°F -23°C |
-12°F -24°C |
-13°F -25°C |
-14°F -26°C |
| 20°F -7°C |
16°F -9°C |
3°F -16°C |
-5°F -21°C |
-10°F -23°C |
-15°F -26°C |
-18°F -28°C |
-20°F -29°C |
-21°F -29°C |
-22°F -30°C |
| 15°F -9°C |
11°F -12°C |
-3°F -19°C |
-11°F -24°C |
-17°F -27°C |
-22°F -30°C |
-25°F -32°C |
-27°F -33°C |
-29°F -34°C |
-30°F -34°C |
| 10°F -12°C |
6°F -14°C |
-9°F -23°C |
-18°F -28°C |
-24°F -31°C |
-29°F -34°C |
-33°F -36°C |
-35°F -37°C |
-37°F -38°C |
-38°F -39°C |
| 5°F -15°C |
0°F -18°C |
-15°F -26°C |
-25°F -32°C |
-31°F -35°C |
-36°F -38°C |
-41°F -41°C |
-43°F -42°C |
-45°F -43°C |
-46°F -43°C |
| 0°F -18°C |
-5°F -21°C |
-22°F -30°C |
-31°F -35°C |
-39°F -39°C |
-44°F -42°C |
-49°F -45°C |
-52°F -46°C |
-53°F -47°C |
-54°F -48°C |
| -5°F -21°C |
-10°F -23°C |
-27°F -33°C |
-38°F -39°C |
-46°F -43°C |
-51°F -46°C |
-56°F -49°C |
-58°F -50°C |
-60°F -51°C |
-62°F -52°C |
| -10°F -23°C |
-15°F -26°C |
-34°F -37°C |
-41°F -41°C |
-53°F -47°C |
-59°F -51°C |
-64°F -53°C |
-67°F -55°C |
-69°F -56°C |
-70°F -57°C |
| -15°F -26°C |
-21°F -29°C |
-40°F -40°C |
-51°F -46°C |
-60°F -51°C |
-66°F -54°C |
-71°F -57°C |
-74°F -59°C |
-76°F -60°C |
-78°F -61°C |
| -20°F -29°C |
-26°F -32°C |
-46°F -43°C |
-58°F -50°C |
-67°F -55°C |
-74°F -59°C |
-79°F -62°C |
-82°F -63°C |
-84°F -64°C |
-85°F -65°C |
| -25°F -32°C |
-31°F -35°C |
-52°F -47°C |
-65°F -54°C |
-74°F -59°C |
-81°F -62°C |
-86°F -66°C |
-89°F -67°C |
-92°F -69°C |
-93°F -69°C |
| -30°F -34°C |
-36°F -38°C |
-58°F -50°C |
-72°F -58°C |
-81°F -63°C |
-88°F -67°C |
-93°F -69°C |
-97°F -72°C |
-100°F -73°C |
-102°F -74°C |
| -35°F -37°C |
-42°F -41°C |
-64°F -53°C |
-78°F -61°C |
-88°F -67°C |
-96°F -71°C |
-101°F -74°C |
-105°F -76°C |
-107°F -77°C |
-109°F -78°C |
| -40°F -40°C |
-47°F -44°C |
-71°F -57°C |
-85°F -65°C |
-95°F -71°C |
-103°F -75°C |
-109°F -78°C |
-113°F -81°C |
-115°F -82°C |
-117°F -83°C |
| -45°F -42°C |
-52°F -47°C |
-77°F -61°C |
-92°F -69°C |
-103°F -75°C |
-110°F -79°C |
-116°F -82°C |
-120°F -84°C |
-123°F -86°C |
-125°F -87°C |


