Sheriff Brian Burnett says the woman's climbing companion called for help Wednesday afternoon, saying his partner slid about 800 feet while descending the mountain.
The King County sheriff's office sent a helicopter but was unable to hoist the woman from the site at the 8,900-foot level due to high winds.
The sheriff's office said Wednesday night a second helicopter was requested through the Air Force Rescue Coordination Center.
Burnett says his office is trying to get a deputy and a medic to the area. The woman was not identified.