The dog days of summer are upon us. In the next few days, temperatures across the region are expected to stay in the mid-80 to mid-90 degree range. So far, and fortunately, there have been no reports that this ongoing wave of heat has claimed any lives in Maine. But, twice in the last 10 days rescue crews were called to aid mountain hikers in Oxford and Franklin counties.

On Saturday, rescue crews, overwhelmed themselves with the exhaustion that can accompany high temperatures, stayed overnight on Surplus Mountain in Andover before bringing an ill 18-year-old to safety.

Last Tuesday, 40 rescuers in Rangeley endured a more than 10-hour effort to help another hiker stricken on a remote section of the Appalachian Trail northeast of Saddleback Mountain.

“It does take a tremendous amount of resources and personnel to pull a rescue off like that,” said rescuer Mike Senecal, a supervisor with NorthStar Emergency Medical Services.

Both efforts involved long treks into steep mountain terrain, which not only put the rescue parties at risk to injury, it also took them out of service making them unable to respond to other emergencies for exceptionally long stretches of time. And, both cases hinged around what is arguably one of the most preventable of all wilderness afflictions: dehydration.

On a normal day the average adult loses about 2.5 liters of water from sweating, breathing and natural body functions, according to the Mayo Clinic in Rochester, Minn.

With temperatures reaching the low- to mid-90s, the past few days have been far from normal. Even the fittest athletes can fall victim to dehydration and the accompanying heat exhaustion brought on in higher than normal temperatures. In fact, just a small reduction in body fluids and electrolytes can lower the total blood volume circulating in a person’s body, according to Mayo. That lower volume means the heart has to pump harder to keep blood pressure up to maintain the body’s organs. That lower blood volume also means normal perspiration and the dissipation of heat is reduced, allowing the body’s core temperature to climb – bringing on heat exhaustion. Most cases of dehydration can easily be resolved by rapidly restoring water and electrolytes to the body.

But there’s an easier way: avoid dehydration in the first place by consuming plenty of liquids, especially water, on a hot day.

On a normal day most people should drink at least 2 liters of water a day.

On hot and humid days, like we’ve seen lately, and under the strain of heavy exertion like hiking with a backpack up a mountain, much more water is needed.

Stemming the risk of dehydration should start at least a full day before a strenuous outing in high heat, which means drinking plenty of water-based fluids while avoiding other fluids that rob the body of water, including alcohol, caffeine and so-called energy drinks.

Mayo advises that “perhaps the best overall recommendation is to make a conscious effort to keep yourself hydrated and to make water your beverage of choice.

“That might mean drinking water with every meal and between each meal; taking water breaks instead of coffee or tea breaks; and substituting sparkling water for alcohol.”

The hikers helped to safety in Rangeley and Andover were lucky that trained rescuers were available to rush to their dehydration emergencies, but both emergencies were highly avoidable had the hikers listened to one of the most common mantras of those who regularly recreate in wild places: hydrate or die.