When the days send shivers down the spine, it's important to bundle up.

Bare skin exposed to the cold for extended periods of time, which often ends up being the nose, cheeks and sometimes the ears, will begin to feel numb and sting. That is the beginning signs of frostbite shares Doctor Denis Fortier, Vice President Medical Services, Chief Medical Officer Southern Health Sante Sud.

"After a while, you won't be able to feel pain anymore, and that is because the structures of that cell and tissue, including the nerve, are now damaged."

When someone comes back inside from the cold, a person may notice that the areas that were exposed and went numb will now look white. That is an indication that cell death has occurred, causing permanent damage.

By definition, frostbite is when a cell becomes so cold, its liquid structure begins to crystallize.

"Each of these cells is sort of a living breathing organism in and of itself; it's got a little chemistry factory going on each one of our cells. When something affects the cells ability to do its work sometimes the cell suffers and sometimes dies," says Fortier.

Fortier explains cells work optimally at a temperature of 37 degrees. If the temperature is too high, it's called hyperthermia, when the temperature is too cold, hypothermia.

The temperature where frostbite sets in is a little different for everyone, says Fortier. However, one of the main factors involved is windchill, or how quickly the wind removes the heat generated by your body.

"The windier it is, the more likely it is for the cells or the surface of your skin to not be able to maintain that temperature of 37 degrees ."

Fortier says during the winter months the best course of action is to bundle up to the best of your ability and listen to weather forecasts, as weather forecasters will let you know how long it will take for exposed skin to freeze.