A helicopter and a plane that flew over Mount Hood for hours before the cloud cover dropped were unlikely to return, said Detective Jim Strovink of the Clackamas County sheriff's office, spokesman for the searchers.
"The weather, that's what's hampering this operation," he said.
Mountaineers who found the body of 26-year-old Luke T. Gullberg of Des Moines, Wash., on Saturday couldn't attempt climbing high on the slopes Sunday because the risk of avalanche increased after an eight-inch overnight snowfall.
"Nobody is going to want to tromp around in that snow," said Steve Rollins, a Portland Mountain Rescue leader.
At nightfall, Strovink said operations had ended for the day and rescuers knew that "time is critical now."
Still, officials say they have not given up hope that 24-year-old Anthony Vietti of Longview, Wash., and 29-year-old Katie Nolan of Portland could still be found alive, calling them experienced climbers.
The three mountaineers had begun their ascent on the west side of the mountain about 1 a.m. Friday and were due back late that afternoon, but failed to return.
On Saturday, crews found Gullberg's body on the glacier at the 9,000-feet level.
His equipment also was found scattered around the glacier, including a camera with at least 20 photos of the climbers. Crews have looked over the photos for landmarks and other clues to the location of the two missing climbers.
"It looked like they were confident and having a good time," Strovink said of the photographs.
Relatives of the three climbers were gathered at Timberline Lodge, a ski lodge on Mount Hood and a staging area for the rescuers, to await more news. They were comforted by Dennis Simons, a nondenominational volunteer chaplain for the police and fire departments in nearby Sandy.
"They are grieving and hoping," he said.
The three climbers, all Christians, met through church activities, Simons said, and Nolan has traveled extensively for Christian causes.
Simons said the experience of Nolan and Vietti also was giving their relatives hope. He said Nolan had made the summit of other Cascade Range peaks, and the three had climbed together before. "They know how to survive in the snow," Simons said.
The Oregonian newspaper reported Sunday that Gullberg was a sales clerk at the outdoor retailer and cooperative REI in Tukwila, Wash., and he studied writing and English at Central Washington University.
Mount Hood is a popular site among climbers in the United States. In 25 years, it has been the site of dozens of climbing accidents and fatalities. The worst on record happened in May 1986 when nine people -- seven students from Oregon Episcopal School and two adults -- died after they dug a snow cave during a sudden storm.
The latest search, which comes almost exactly three years after another trio of experienced climbers died on Mount Hood during a December 2006 blizzard, has generated heated debate among some about the wisdom of tackling the mountain during the winter, a season when brutal storms can move in quickly.
In an online discussion for climbers at www.summitpost.org, some said it's irresponsible even for experienced climbers to take on Mount Hood during the winter while others said the challenge of winter mountaineering is what brings them to Mount Hood.
Veteran climber Jim Whittaker, the first American to conquer Mount Everest, said he understands why climbers like the challenge of tackling Mount Hood in the winter.
"It's exciting and fun when your testing yourself against the power of nature," Whittaker said in an interview from his home in Port Townsend, Wash. "But you've got to know what you're doing; you've got to be prepared."
Republican John Lim, a former legislator who's running for governor, said Sunday he plans to keep pushing for a state law to require mountaineers to carry electronic locator devices when they head for the summit of Mount Hood.
"With electronic beacons, you can locate a person right away and save their life instead of ending up with a dead body," Lim said.
Many rescuers and mountaineers oppose such a requirement, saying it would create a false sense of security and prompt some climbers to take risks they otherwise would avoid.
In the latest case, the three climbers did not have a radio locator beacon but they did have a cell phone that was briefly activated as they were preparing to begin their ascent.