Kara O’Brien and Jeff Mayhew, with the Southern Arizona Rescue Association, return from walking along the Ventana Canyon Trail after searching for a lost hiker in the Santa Catalina Mountains outside Tucson. (A.E. Araiza/Arizona Daily Star via AP)

The Pima County Sheriff’s Department said Tuesday that after a day-long search in heat-scorched Ventana Canyon they had recovered the body of 33-year-old Marcus Turowski. He was one of three men from Germany who set off hiking over the weekend, only one of whom returned alive.

They were hiking on the Ventana Canyon Trail in the Santa Catalina Mountains just north of Tucson on Sunday, but heat in Arizona soared dramatically. That day, for example, temperatures rose to 120 degrees, breaking the record in Yuma, Ariz., set in 1960 by 5 degrees. Meanwhile, Phoenix set a new daily record when temperatures rose to 118 degrees, breaking the 1968 record by 3 degrees.

As temperatures began cresting above 115 degrees in the mountains, the heat drained the hikers and their strength so insidiously that only one could walk to summon help. The others lay helpless, baking on the trail.

It’s unclear if the hiker who managed to walk back down the trail informed a passerby of the situation or if one found the stranded hikers, but someone called 911, which led to the deployment of a search party. One of the men’s bodies was found on Sunday, about four miles away from the trailhead, according to a statement from the Pima County Sheriff’s Department. The other, that of Turowski, was found on Tuesday at 7 a.m.

“It really shows how critical this heat can be and how it can really sneak up on you,” Capt. Larry Subervi, a Phoenix Fire spokesman, told the Arizona Republic. “When we deal with temperatures like this, it can just really be unpredictable how your body is going to respond.”

Turowski’s death was at least the fifth heat-related fatality in Arizona since Friday.

On Saturday, 25-year-old Anthony Quatela III and his friend ran out of water while hiking on the Peralta Trail on the Superstition Mountains. As temperatures soared to 111 degrees, Quatela fell unconscious from heat exposure, Grind reported.

He never woke up.

Then, on Sunday morning, an unnamed 28-year-old woman was biking with friends on the Phoenix Mountain Preserve when she stopped breathing and died. Meanwhile, a 19-year-old female hiker died on the Finger Rock Trail after collapsing from the heat.

Several others are being treated in area hospitals.

(National Weather Service)

Speaking about the German hikers, Pima County Sheriff Chris Nanos said everyone should stop all kinds of outdoor activities during the heat wave.

“It’s all because they make a choice. All of this is 100 percent avoidable,” Nanos said, NPR reported.

Subervi agreed.

“When we deal with temperatures like this, it can just really be unpredictable how your body is going to respond,” Subervi told the Arizona Republic. “Even backyard barbecues can be dangerous on a day like today.”

The human body isn’t made to withstand extreme heat, and heat stroke can occur when the body temperature exceeds 104 degrees. The early signs: throbbing headache, dizziness, muscle cramps, nausea, disorientation and — counter-intuitive as it might sound — lack of sweating.

Claude Piantadosi, a professor of medicine at Duke University, told Time that heat exhaustion will almost always result in death — in a matter of hours — if not treated immediately.

Dehydration, of course, plays a major factor in these deaths. Generally while hiking, the body loses about a liter of water each hour. That number is more than doubled in hot weather. The rub is that the body cannot absorb water nearly that quickly, so it’s nearly impossible to replace even if a hiker is carrying enough. Instead, it can only efficiently absorb a half-liter every hour, Modern Hiker reported.

In other words, each hour, the body can lose 2 liters of water but only replace .5 liters, leaving the body at a 1.5-liter deficit of water each hour.

Lost with that water is sodium and potassium, so it’s important to replace those minerals in the body with trail mixes, fruits or an electrolyte-filled drink like Gatorade.

Subervi suggests avoiding outdoor activity during this heat wave. But if hikers insist, he said, they should begin hydrating 24 hours before a planned hike then drink 32 ounces for each mile they travel.

“You have to prepare your body,” he said. “Your body will be fighting the weather in this heat.”