Mark Thomas, 26, managed to hike to safety on Monday, but he had to leave his friend Thomas Bennet, 26, behind.
Rescue crews tried to reach the men earlier on Monday, but the wind was so strong, it knocked them right out of their skis.
Thomas's father, Jay Thomas, says his son is an experienced mountain climber and he knows Mt. Shasta very well.
"He's been climbing for about 10 years. He's in extraordinary condition in terms of physical and cardiovascular," said Jay.
But Mark realized on Monday there was nothing more he could do for his friend, Bennet, who appeared to be suffering from altitude sickness. Thomas became disoriented, kept losing his balance, then he lost consciousness, and has been unresponsive since Sunday afternoon.
So Mark built him a snow cave and left him near the summit of Mt. Shasta in search for help.
"I suspect that the wind and the weather caught up with him, as well as his partner's altitude sickness. I don't know which came first, but Mark has shown very good judgment when he's been in difficult situations before," said Jay.
Even with their experience, a mountain climber at sporting goods store R.E.I. told ABC7, climbers can quickly get into trouble.
"Going from low elevation to high elevation, just overnight, can really catch up with you quickly," said REI employee and mountain climber Andy Miksza. "You have to take steps to adjust to the elevation, and hydration is definitely key. Elevation sickness can creep up on anybody. You can be in extremely good physical condition and take all of those precautionary steps and still get caught in a situation, unexpected."
Mark was able to call authorities and tell them approximately where he was located, but the weather kept search crews from launching a helicopter.
"It's difficult, especially during storms, for us to get anyone up there. And oftentimes the mountain makes its own weather and it this particular time there was a big storm that came into our whole county," said Susan Gravenkamp from the Siskiyou County Sheriff's Office.
They did send out two searchers on snow mobiles. They eventually found Mark, who had almost reached safety on his own. He was only two miles from the search base camp when the crews spotted his footprints and tracked him down.
Mark is a UC Berkeley graduate and does research at the university. He has frostbite on one of his fingers, but otherwise he is physically OK.
Bennet lives in Oakland. Rescue crews will check the weather in the next few mornings to see if it is clear enough to launch a helicopter. They likely won't be going up on the mountain until Thursday, after the storm passes.