Doug Whipper and his friends were enjoying a seemingly perfect day skiing Tuesday when Whipper noticed a small patch of white skin on his friend's cheek.
"When that type of discoloration appears -- and you know that the temperatures are very low -- those spots are a sign of frostbite," he said.
Whipper, a Colorado Moun-tain College wilderness study program professor, immediately told his friend to cover his face until they could get to a building to warm up.
When temperatures drop as low as they are expected to tonight and Thursday morning, Whipper said everyone needs to realize he or she is in danger of suffering from hypothermia and frostbite.
"When they call for temperatures to dip into the 30-below range, that's dangerous to be outside.
"If you're not protected, you will freeze to death really quickly," he said.
Whipper said that exposed skin, including hands, feet, noses and cheeks, freeze quickly when temperatures drop below zero. It is not always easy to treat hypothermia or frostbite, which is why Whipper recommends people dress in layers, stay inside if possible, and carry emergency items in cars, backpacks or purses.
"People who live in the city rely on their technology, then their technology fails and they die," he said.
Whipper warns people to not depend too much on cars because he has known commuters who have slid off highways or roads and been stranded without food or warmth.
Whipper also advises people who are outside -- even briefly -- to dress in multiple layers and to not let any part of their skin be exposed to the wind or snow.
Whipper warns that most winter clothing is not designed to protect people against minus-20 degree temperatures and that is especially true of children's clothing.
"Kid's skin is just as vulnerable as an adult's. They will freeze just as fast as we will," he said.
For that reason, Whipper advises parents to drive their children to school when temperatures are so low or to let them stay in a running vehicle until the school bus comes.
Yampa Valley Medical Cen-ter emergency room physician Larry Bookman said that in the past week he has treated one skier with a case of mild hypothermia.
Bookman advises people to be aware of their surroundings when it is cold because it does not take very long for mild hypothermia to turn into something more severe, such as frostbite.
Bookman advises people who are noticeably cold or shivering to move to a warm building because shivering is the first sign of hypothermia.
"The best way to warm up is to sit in 140-degree water or anything warm, really. It might be painful and hurt like crazy, but you have to warm those areas immediately," he said.
Bookman said most people could treat minor hypothermia relatively easily by adding layers or covering affected areas with a scarf or blanket.
"People just need to use their common sense when it gets cold and be prepared," he said.