Mount Thielsen Professional Review and Guide
"Few of Oregon’s signature Cascades has as dramatic a profile as Mount Thielsen. It’s one of the state’s most overlooked peaks, perhaps only because it’s not located conveniently at the edge of a major metropolitan area. None of the other Cascades juts as pointedly into the skyline as this peak does. It has inspired mountaineers for decades, if only after they’ve had their fill of Mount Hood’s crowded slopes. This route does not detail the full climb to the top of Mount Thielsen, because getting there in the winter (snowshoeing season) involves serious mountaineering skills.
Instead, the route leads to a beautiful ridge that takes you right to the base of the summit spire, with expansive views of the Diamond Lake and Crater Lake country. From this spot, even Mount Bailey looks like a low hump on the horizon. Also, you can do this route as late as June or even July, depending on the snow year. You might have some dirty snow at the forested base, but in general this is a great hill to head for when the sun is shining and the days are longer. Located as it is in the southwestern Oregon mountains near Crater Lake, its weather is generally more favorable than the west side of the Cascades; there is more sun here and less prevailing fog and mist."