Anyone who participates in outdoor wilderness activities should be aware of hypothermia--what it is, and how to prevent it. It may surprise you that temperatures don't have to be below freezing. In fact, most cases occur between 30 and 50 degrees Fahrenheit, temperatures not all that unusual during a Florida winter. Boaters, especially, should be mindful, particularly when water temperatures dip below 60 degrees.
How Hypothermia Progresses
Hypothermia often goes unrecognized in its early stages, when you have your best chance of doing something about it. Initially, you may shiver and feel cold, but think you're fine. Your skin gets pale and cool, as blood retreats to your body's core. Your fingers may get stiff, and you may find it hard to do simple things like zip your jacket or light a match. You lose your ability to concentrate. At this stage, hypothermia may not seem like a big deal.
But let it get much worse, and before you've sensed any real danger, something awful happens--your brain cools so much that you're no longer mentally capable of self-help. At this point, you're done, UNLESS...someone's there to help you. Your cold-brain problem may cause you to do stupid things, such as take off your jacket, or fail to get out of the wind or rain when you could easily do so.
As long as your environment continues to suck life-giving heat from your body, your condition worsens. You lose muscular coordination, and can no longer walk properly. You begin to stumble, your speech becomes slurred. You may mutter under your breath. Personality traits change. If you're normally positive, you may complain; if you're normally talkative, you may get quiet. Your mental confusion becomes more pronounced.
Eventually, you stop shivering. Not because you've warmed up, but because shivering--the body's way of warming itself--requires energy, and yours has mostly run out. Your body can no longer re-warm itself, even inside a fluffy, fat goose-down sleeping bag. At this stage, your life is in grave peril. Rewarming you is problematic, and it's going to take expert medical help to do so. You may be semi-unconscious, or you may be totally out.
The Face of Hypothermia
In this section, you'll find a six-minute video I did to show the effects of the early stages of hypothermia. I purposefully put myself into a mild hypothermic state to demonstrate for you what to watch for in yourself and your companions. Notice the shivering, shaking, and halting speech. It's taking me a lot of effort here just to think and put words together.
Many times, someone displaying these signs will insist they are fine. Trust what you see, not what they say. Insist on helping them to re-warm right away. DO NOT allow this condition to worsen, in you or in your companions.
Hypothermia has been compared to a dangerous predator. It sneaks up on you with great stealth. At some point, it pounces, and overcomes you before you know what happened.
Recognize this condition, and avoid it.
How to Avoid Hypothermia
The short answer: Don't get cold. At home, this is easy to do. Just come indoors and crank up the thermostat.
In the wilderness, however, staying warm takes thoughtful pre-planning.
For starters, you need the right kind of clothes. Ideally, you want layers. First, a snug polypropylene underwear layer next to your skin, capable of wicking away perspiration. Next, quick-drying pants, shirt, and maybe a wool sweater, or nylon fleece. Most experienced wilderness folks avoid cotton. Cotton is comfortable when dry, but when it gets wet, it's hard to dry, it's heavy, and it won't insulate you. Finally, you want a windproof outer shell.
If you heat up, remove some layers. You'll cool off, and your sweat will evaporate into the air, keeping you and your clothes dry. (Focus on staying dry.) If you start to cool too much, add back some layers.
Always carry with you some way to start a fire. I prefer a pocket knife and a magnesium fire starter because these will start a fire even if they get wet. Just dry them, and you're in business.
Also don't be without emergency shelter from the wind and rain. A space blanket, 30 feet of parachute cord, and some duct tape, make a fast and effective shelter. Keep this stuff in a small survival kit always on your person.
Be competent in the ways of the wilds
This information is not meant to scare you away from wilderness pursuits, but to help you become more competent in the ways of the wilds.