Hypothermia-- a real danger, even in Arizona

Contrary to the popular view of Arizona, a large portion of the state is at higher altitudes. As I noted in my last post, the North and South Rims of the Grand Canyon are both over 7000 feet above sea level. The northeast third of Arizona lies on the Colorado Plateau, most of which is over 5000. Temperatures in the Arizona high country can go as low as 40 degrees F below zero which was recorded at Hawley Lake at 8,180 feet above sea level. However, one hallmark of the high country in Arizona is the wind. It is not unusual for the wind to blow almost constantly at over 30 mph. With a wind chill factor, that -40 degrees F would have been the equivalent of the lowest temperature ever recorded in Alaska, -80 degrees F. NWS Wind Chill Chart

At those low temperatures the average time to frostbite can be as low as five minutes. But it does not take such extreme temperatures to put someone in danger of hypothermia. The primary indication of hypothermia is a core body temperature below 95 degrees F (35 degrees C). Below that temperature, hypothermia is life threatening. With the contrasts in temperature varying by altitude, you can leave Phoenix at a balmy 60 or 70 degrees F and within an hour or so, step out of your car into below freezing temperatures. Additionally, the temperature can vary significantly during twenty-four hours most places in Arizona, especially at altitude. For example, in the winter, Flagstaff can have a temperature variation of over 30 degrees from day to night.

Hypothermia can occur whenever the ambient temperature is lower than the body temperature. Obviously, the lower the temperature outside, the greater the danger. Hypothermia can be classified into three stages, mild with a core body temperature above 89.5 degrees F, moderate with a core body temperature over 82.4 degrees F and severe when the body temperature falls below 82.4 degrees. Young people and those with little or no body fat are at greater risk of hypothermia. The main symptoms of mild hypothermia are shivering, lethargy, confusion, loss of coordination and rapid heart rate. As the hypothermia gets worse, the shivering stops and confusion becomes delirium. At very low temperatures, the heart stops and you die.

Don't treat excursions out into the Arizona wilderness lightly. Temperature conditions can be extreme.

Next time: Heat exhaustion and heat stroke