Defeat Heat Thieves
» Radiation Any time air temperature is below 98.6°F, bare skin vents heat. Fix Cover exposed skin with gloves, a hat (A), neck gaiter, and a face shield. Go inside a shelter, which traps body heat.
» Evaporation During a tough hike, cooling sweat could drench your layers—and drying them wastes energy. Fix Adjust pace and clothing to avoid excess sweating, and slow down 30 minutes before reaching camp to let body heat dry baselayers.
» Convection Moving air cools skin fast—that’s why windchill makes temps feel colder. Fix Wear windproof outer layers, seek shelter (B), and plan a route with minimal wind exposure, like a forest or a canyon.
» Conduction Contact with frigid surfaces siphons heat as the temperatures equalize. Fix Insulate sleeping and sitting surfaces with your pack or sleeping pad (C), or even dry leaves.
Eat Your Way to Warmth
» Switch to a high-fat diet. Calorie-dense foods like chocolate, nuts, and cheese metabolize slowly, prolonging digestion’s hour-long, body-warming effect.
» Drink green tea. Catechin-packed tea boosts metabolism, and hot drinks
in general cause sensors in your
arteries to shuttle more blood to your extremities, making you feel warmer.
» Add oil and spices. Olive oil is a caloric H-bomb, and eating mild spices (ginger, nutmeg, and cinnamon) increases blood flow to the skin. Beware of capsaicin in hot chilies; it’ll make you sweat.
Predict the Weather
» Plan around fall weather windows. One-third of North American storms occur in September; October’s weather is typically worse during the first half of the month; and in November, precip decreases in many parts of the country, especially the South and Southwest.
» Avoid autumn’s bad-weather systems. Watch the forecast for regional patterns that bring extended wet and cold. In the East, avoid slow-moving Nor’easters that pummel mountains and coasts with wind, rain,
and snow for days. In the upper Midwest and Great Lakes regions, low-pressure Alberta Clippers mean a week or longer of frigid temps. In the South, disintegrating tropical storms bring 24-hour wind, rain, and high humidity. In the West, Pineapple Express storms can drown trails between the Sierra Nevada and the Cascades.
» Go to good weather. Mild conditions and few crowds make fall ideal for hiking in many life-list destinations. Plan big trips to Yosemite National Park, Utah’s Canyonlands and Grand Staircase-Escalante, or the Smokies, where October is peak color season and daytime highs remain in the 70s.
» Avoid low pressure cold fronts. These systems bring rain and cold.
Plan a Warmer Route
» Hike near large bodies of water. Oceans and substantial lakes can moderate air temperatures and weather systems nearby. That’s because large volumes of water cool more slowly than air and land, so even when the ground is frozen, the water will be warmer. Beware of small bodies of water. Low-volume pools or streams can have a cooling effect, because overnight air temperatures can chill them. In turn, they cool surrounding air into the next day.
» Explore canyons and gorges. Where elevation differentials are extreme, gorge bottoms—with sun exposure—can be hot spots. At the Grand Canyon, October’s average in-
canyon high is 19 degrees warmer than at the South Rim.
» Watch your elevation. Air temperature drops 3° to 4°F for every 1,000 feet of elevation gain, which means that a trailhead drizzle can turn to flurries as you climb.
Coldproof Your Camp Kitchen
» Pack a white-gas stove. Below 40°F, canister fuels gradually lose the ability to vaporize, so the canisters lose fuel pressure, resulting in a weaker flame. Below 15°F, most canister stoves will sputter and stop. White-gas stoves are more reliable in cold temps because they use preheated priming cups to vaporize fuel, and their refillable bottles have manual pumps, which enables you to maintain adequate fuel pressure.
» Keep canister fuel warm. Never warm a canister near flames. Instead, use your body heat; tuck it inside your jacket or store it in the foot of your sleeping bag during the night. While cooking, place it in a pan of water, which will be warmer than freezing air.
» Carry more. Pack at least five fluid ounces of white gas or 3.5 ounces of canister fuel per person per day.