Like the song says, it is cold outside, dangerously cold, actually.
 
Consider limiting the amount of time you spend outside, particularly if temperatures are so cold that you can suffer frostbite. Hypothermia – abnormally low body temperature – is an ever-present danger during winter. Severe hypothermia is a medical emergency that can cause an irregular heartbeat and lead to heart failure or death.

While hypothermia happens most often from a long period of exposure to very cold temperatures, even cool temperatures above 40°F or 4°C can be dangerous to a person who has become chilled from rain, sweat, or being in cold water for an extended period of time. 
Below are some more safety tips for cold weather.  These are mostly common sense tips, but it never hurts to be reminded of them.

1. When outdoors, dress warmly, but choose loose fitting, layered,  lightweight clothing. Wear a hat and protect your hands, ears and neck.
2. Your feet need protecting too, particularly when it is slippery outside. Shoes and boots should have non-skid soles. Wear rubber sole boots for better traction in the snow.
3. Definitely wear a hat or scarf, but be careful not to block sound altogether, or for that matter, your vision.
4. Protect your skin with heavier lotions and creams.
5. If you use a cane, replace the rubber tip before its worn smooth as it will become slippery when it gets wet.
6. To reduce the chance of falling when leaving the house, use rock salt, sand, or some other de-icing compounds to prevent falling on ice that may be on the steps and/or walkways.
7. Know your physical limitations, especially if you are working outside. Do not over exert yourself. Be aware of the signs and symptoms of a heart attack such as nausea and chest pains.
8. Make sure your smoke and carbon monoxide detectors are working at home.
9. Never use your range or oven to heat your home. 

Visit the Saint Peter’s Better Health Library for information on recognizing signs of hypothermia.