Although rare, frostbite can happen in the backyard as well as on a mountaintop -- and cause permanent injury. Frostbite is when blood vessels constrict due to extreme cold and cause tissue damage.
The best defense against it is to layer your winter clothing, says Dr. John Loiselle, associate director of emergency medicine at St. Christopher's Hospital for Children in Philadelphia. Exposed hands and feet are the most vulnerable.
Here's what frostbite looks and feels like:
If you suspect frostbite, cover the area with a warm, dry cloth. It's even better to place the affected body part in warm water (no hotter than 104 degrees F). Either way, seek medical help immediately.