Nighttime temperatures in Yosemite National Park are expected to dip to 30 degrees or lower this month and by December, lows will average just 26 degrees. Despite the chill, Yosemite and other campgrounds will draw a good share of hardy winter campers: Each month during the winter, about 3,000 people camp at Yosemite’s four, year-round facilities, according to a park spokeswoman. As their reward, they will enjoy the park in relative quiet, as compared with the experience shared by the 100,000 campers monthly that visit during the summer.
But staying healthy during winter camping requires special preparation. While heat exhaustion and some other dangers of hot-weather travel are not a problem, there are other concerns to be aware of, including hypothermia (a dangerous drop in body temperature) and frostbite (freezing of the tissues).
Paying attention to bedding and other gear, clothing, wind conditions and especially to early symptoms of cold injuries can help winter campers stay in good health, according to Dr. James A. Wilkerson, a pathologist, wilderness medicine expert, author of “Hypothermia, Frostbite and Other Cold Injuries” (The Mountaineers Books, $11.95 paperback) and editor of “Medicine for Mountaineering & Other Wilderness Activities” (The Mountaineers Books, $16.95, paperback).
Special winter gear, such as cold weather masks and battery-operated heated socks and gloves, is sold at sporting goods stores. But some say old-fashioned attire can keep you just as warm.
No matter what the destination, cold weather campers “have to be prepared for zero degrees,” Wilkerson said. “You’re not going to get it very often, but be prepared for it.”
That means having a good sleeping bag, and most experts advise buying one rated for zero-degree environments. In addition, plan to use an insulated pad between the sleeping bag and the ground, Wilkerson advised. Two are even better.
For cold weather sleeping bags, “nothing beats down,” Wilkerson said, “but polyester is probably just as good (for warmth).”
Clothing should be thick and insulating, Wilkerson added. “Wear down-filled or polyester jackets, long underwear, pile pants and waterproof outer pants,” he suggested. Don’t forget gloves.
Dress in layers, advised Steve Ferguson, who works at REI, an outdoor gear and clothing store in Northridge. The layer closest to the skin should be made of a material that can wick away body moisture (cotton, for example), he said. The middle layer should ideally be of fleece or down for warmth. The outer layer should be water resistant and breathable to protect from the elements (Gor-tex or Polartec, for example).
No matter how cold the evening, change clothes before going to sleep, Wilkerson said, to rid the body of perspiration-soaked clothes that could cause a chill while the camper rests.
Some sporting goods stores even sell battery-operated socks and gloves to generate warmth. “But the batteries don’t last that long (perhaps a few hours, used continuously)” Wilkerson said, “and should not be depended upon. Keep your body warm and your hands and feet will stay warm, too.”
Another option for keeping warm is cold weather masks, similar in appearance to those worn by gardeners to avoid breathing dirt and pollution. But a wool scarf pulled up from the neck that can also cover the cheek area is probably just as good for maintaining body heat, Wilkerson said.
And a good winter tent is essential, Wilkerson and others agree. Four-season tents are usually constructed with more poles than other tents, according to Ferguson, allowing them to better withstand rain, snow and wind.
Staying warm can minimize the risk of hypothermia, a potentially fatal condition that can affect functioning of the heart, intellect and muscles.
At its mildest, Wilkerson said, hypothermia usually involves a body temperature below 98 but above 90 degrees; in severe cases the temperature may drop below 90 degrees. He has nicknamed the first symptoms of hypothermia, the “umbles”: A person fumbles, mumbles, stumbles and bumbles, as the temperature decline affects muscular and intellectual functioning.
In mild stages, people with hypothermia sense skin numbness and chilliness, Wilkerson said, and may notice trouble performing fine hand movements. Then comes lack of coordination and weakness, stumbling and mild confusion.
As hypothermia becomes more severe, shivering may stop and the person may be unable to walk or stand and, finally, may lapse into unconsciousness.
Treat hypothermia as soon as symptoms become apparent. “Do all the things your mother told you (to do in cold weather),” Wilkerson said. Warm the body by covering it and take the person inside. “If someone is so cold they have lost consciousness, it’s an almost desperate situation,” Wilkerson said. In severe hypothermia, he added, the heart is especially prone to the life-threatening condition, ventricular fibrillation (irregular heartbeat). Moving and jarring can set it off, so in recent years, rescue teams have begun trying to rewarm victims before evacuating them.
The body temperature must rise to at least 90 degrees before the heart will beat normally, Wilkerson said. Getting professional medical help immediately is essential.
Another danger associated with cold-weather camping is frostbite. Pain is usually the first symptom, but then subsides, usually for one of two reasons, Wilkerson said. “Either you have warmed up or the tissue has become frozen.”
Most commonly affected are hands, feet, ears and face, in particular the tip of the nose. The area “looks like it is frozen,” Wilkerson said, almost becoming white.
Boots and other garments tight enough to inhibit circulation are an often overlooked cause of frostbite. Winter campers must be doing something right, though. Statistics indicate that they are less prone to frost injury that one might think. “Frostbite is more common in cities than in the wilderness,” Wilkerson said.
Even equipped with the best down-filled sleeping bag and winter camping wardrobe, some people should avoid winter camping, Wilkerson said, including those with vascular problems and with circulatory problems in their feet.
The Healthy Traveler appears the second and fourth week of every month.