The ground search for Eric Fernandes was halted Tuesday on Camelback Mountain.
Phoenix police spokesman Sgt. Trent Crump says search crews have covered the area they can by foot and there is no sign of Fernandes.
Temperatures in the area reached 110 degrees on Monday.
Crump says people in distress on the steep, rocky mountain can be hard to spot if they have fallen into crevices.
He says Fernandes was last seen Saturday on top of the mountain by other hikers who said he was alone. They described him as surprised by the difficulty of the hike.
Investigators left a poster with Fernandes' photo and other information on the Camelback Mountain trailheads.
Fernandes, of Seattle, had been visiting the Phoenix area with his father. He reportedly planned to hike the popular mountain Saturday before heading home. Fernandes' father reported him missing Sunday and authorities began the search.
Investigators found Fernandes' car at a Camelback trailhead and have recovered receipts that indicate he bought a hydration backpack and some water.
Police say Fernandes' cellphone died sometime between Saturday night and Sunday morning.
Fernandes' family is pleading for the public's help in finding him.