If you intend to travel outdoors, you should be prepared to deal with all sorts of weather. This might mean the rainiest days to the driest, and from the hottest daytime hours to the coldest nights.

The human body has a normal core temperature between 98.6 and 99.9 degrees Fahrenheit (F). In order to maintain this temperature without the aid of any warming or cooling device, the external environment must be at about 82 F. Clothes aren’t just a social convention — they’re necessary warming tools. We can usually add on more layers in colder months, and use fans or air conditioners in warmer months in order to maintain that healthy core temperature.

However, in some cases, you may find yourself in an environment with temperature extremes. It’s essential to know what health concerns you may face, and how to avoid any temperature-related problems.

The Heat

It’s important to note that the temperature reading on a thermometer is not necessarily the temperature for which you should be concerned. The relative humidity in an environment can significantly affect what’s called the “apparent temperature,” or the temperature you actually feel. If the air temperature reads 85 F, but there’s zero humidity, it will actually feel like it’s 78 F, whereas the same air temperature in an environment with 80 percent humidity will feel like 97 F.

High environmental temperatures can be dangerous to the human body. In the range of 90 to 105 F, heat cramps and exhaustion may occur. Between 105 and 130 F, heat exhaustion is almost certain, and activities should be significantly limited. An environmental temperature over 130 degrees F is likely to lead to heatstroke.

Heat-related illnesses include:

  • heat exhaustion
  • heatstroke
  • muscle cramps
  • heat swelling
  • fainting

One key to avoiding heat-related illness is to stay well hydrated. You should drink enough fluids that your urine is light colored or clear. Never rely solely on thirst as a guide to how much liquid you need to drink. In times of high fluid loss or significant sweating, be sure to replace electrolytes as well. Make sure you wear clothing appropriate to the environment. Clothes that are too thick or too warm can quickly cause a person to become overheated.

The Cold

As with high temperatures, when it comes to cold temperatures, don’t rely solely on the thermometer reading of environmental air. For instance, the speed of the wind and external body moisture can cause a chill that dramatically changes your body’s rate of cooling and how you feel.  In very cold weather, especially with a high wind-chill factor, you can rapidly experience the onset of hypothermia. Falling into cold water can also result in immersion hypothermia.

When your body first drops below 98.6 F, you may:

  • start to shiver
  • have an increased heart rate
  • have a slight decrease in coordination
  • have an increased urge to urinate

When your body temperature is between 91.4 and 85.2 F, you’ll:

  • decrease or stop shivering
  • fall into a stupor
  • feel drowsy
  • be unable to walk
  • experience quick changes between rapid heart rate and breathing to slow heart rate and shallow breathing

Between 85.2 and 71.6 degrees F, you will experience:

  • minimal breathing
  • poor to no reflexes
  • inability to move or respond to stimuli
  • low blood pressure
  • possibly coma

A body temperature below 71.6 F is extremely dangerous. It can result in muscles becoming rigid, blood pressure becoming extremely low or even absent, heart and breathing rates decreasing, and can lead to death.

It’s essential to protect anyone experiencing early symptoms of hypothermia. They should be removed from the cold immediately if possible. However, don’t try to warm a person suffering from serious hypothermia with vigorous exercise or vigorous rubbing, because this can lead to more difficult problems.

Other cold-related illnesses include:

  • frostnip
  • frostbite
  • trench foot (or “immersion foot”)
  • chilblain
  • Raynaud’s phenomenon
  • cold-induced hives

Besides these illnesses, winter weather can cause major inconveniences for travelers. It’s important to be prepared to deal with heavy snow and extreme cold when on the road or at home.