How wind chill calculator Works
The formula
WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T·V^0.16 (T in °F, V in mph) — the NWS/Canadian collaboration formula, valid for T ≤ 50°F and V > 3 mph. It models heat loss from exposed skin: wind strips the warm boundary layer your body maintains, accelerating heat loss exactly like the formula's exponent captures.
The frostbite timeline
The index exists for one purpose: frostbite risk on exposed skin. At −18°F wind chill, frostbite arrives in ~30 minutes; below −30, in under 10. The calculator prints the timeline band — the number that decides whether the walk happens, the gloves come out, and the dog gets a short route.
What wind chill does NOT do
- It does not cool objects below air temperature — pipes freeze at 32°F actual, cars cool to actual temp, tomatoes die at actual temp. Wind chill is a living-tissue index.
- It does not apply in still air (below 3 mph) or warm air (above 50°F) — the concept is undefined, not merely small.
- It does not stack with wet — wet skin loses heat faster than any dry-wind formula models; water is its own emergency.