Utah residents Kyle Dempster and Scott Adamson set out August 21 to climb the north face of Ogre 2, near the Choktoi Glacier, authorities said.
They have not been seen since August 22, the day before a storm hit the mountain.
Pakistani authorities had delayed dispatching rescue crews because of weather conditions, local official Muhammad Iqbal said. The 23,000-foot peak sees intense snowstorms and bad weather this time of the year, complicating search efforts.
Family spokesman Jonathan Thesenga said Saturday that improved conditions would allow helicopters to search for the men -- the first weather break in 10 days.
Later that night, he said an intense search had not yielded any signs of them.
'An extremely difficult time'
"The search has been called off," Thesenga said. "It was an extremely difficult time for the friends and family waiting and hoping for good news. And it's been devastating to come to the decision to call off the search."
He said loved ones had remained optimistic that the men would be found, and are trying to come to terms with the fact that they are not coming home.
"There were a couple of deciding factors in calling off the search, one was the time they had been gone -- the very small amount of hope we had was gone," he said.
"When the extensive search did not yield any visible signs, they made the decision that it would not be wise to risk (this) dangerous search mission with helicopters."
The climbers' initial plan included five days for the climb and descent, the Alpine Club of Pakistan said. They did not return on the expected date, sparking concerns.
Dempster is from Salt Lake City while Adamson lives in nearby Provo, Utah. The two friends tried to summit the treacherous north face of Ogre 2 last year -- but turned back after Adamson fell and broke his leg, according to CNN affiliate KUTV
Ogre 2 is one of the steepest peaks in the region and was ascended only three times between 1977 and 2012, said Ayaz Shigri of the Baltistan Tour Operator Association.