Wind chill - Minutes to Frostbite
These are charts letting you know how many minutes it will take to begin to develop frostbite at different temperatures and wind speeds. Note that the charts are Canadian so the temperatures are Celcius and the windspeeds are in Kilometers.
Wind Chill Hazards
This is a chart letting you know the risk at certain temperatures and how to dress for them
This little paragraph at the bottom there is interesting!!
"**In parts of the country with a milder climate (such as southern Ontario and the Atlantic provinces except Labrador), a wind chill warning is issued at about -35. Further north, people have grown more accustomed to the cold, and have adapted to the more severe conditions. Because of this, Environment Canada issues warnings at progressively colder wind chill values as you move north. Most of Canada hears a warning at about -45. Residents of the Arctic, northern Manitoba and northern Quebec are warned at about -50, and those of the high Arctic, at about -55."
This is the entire WindChill site which Environment Canada has put together. It includes all sorts of charts, online calculators, scientific equations, and so on:
And if, for some reason, you are not familiar with the metric system... here's a conversion site that will help: