Mt. Redoubt is a massive peak, presenting a tantalizing objective from points south in the North Cascades National Park. From the north, the impression is of craggy battlements and serac-filled glaciers. There are two popular routes on the mountain: the technical Northeast Face (snow/ice to 60 degrees and low-5th class rock), and the South route, which involves a pleasant glacier walk around one side of the mountain to reach scree or snow slopes below the summit block. Both routes end with an exciting scramble.
The first ascent was made by J. Cherry and B. Ross in 1930. The rock is Skagit Gneiss, not especially great for rock climbing.
There are other routes on the mountain that deserve more attention. The Flying Buttress is especially enticing. First climbed by Pete Doorish and Alex Cudkowicz in 1989, it climbs an impressive cliff above the Depot-Redoubt Creek Divide (7760 feet) then continues on ridges to the summit (III-IV, 5.9).
The climb is usually approached from the southeast end of Chiliwack Lake in Canada. An overgrown road (4 wheel drive required to drive all the way) leads to a 2 mile walk on an even more overgrown road, then the U.S.-Canadian border. From here, follow a long trail southeast up Depot Creek to an amazing waterfall. After dealing with an exciting fixed-rope climb, ascend the left side of the falls on good-but-steep trail to reach the basin below Mt. Redoubt.
Climbers bound for the Northeast Face can wade several braids of the creek here to set a camp on moraines below the face. They can also continue up to Ouzel Lake for a good camp. Climbers interested in the South Route would find Ouzel Lake a great camp too.
Klenke wrote this approach up so well on his page for Mount Spickard, let me send you over there for exact milages. I strongly advise printing out his schematic map for the end of the road and first mile of trail. For our trip this year, it was our sole "beta" until reaching the base of the mountain, and served us well.
P.S. - as Klenke notes elsewhere, U.S.-based climbers shouldn't tell the border guards they plan to cross back into the U.S.. Instead, promise to climb Slesse Mountain :-).
The mountain is in the North Cascades National Park and a permit is required to camp overnight. The permit is difficult to obtain, requiring a stop in Sedro Woolley, Washington. This isn't that far out of the way for climbers coming from Puget Sound, but presents an unreasonable (in my view) burden for Canadian climbers. Hopefully a self-registration system will be devised for this unusual entry to the park.
A helpful tip for this situation from posmith: "If you speak to the permit desk at the North Cascades Park, they will often give you a permit over the phone the day before or the day of the climb. I got a permit as I cruised up I-5, although it took some explaining."
The climb can be made in spring, summer and fall via the South Route. Avalanche conditions in spring could be a problem, as there is moderately steep snow on south-facing slopes. My impression is that spring would be a lot of work, thanks to huge amounts of snow walking, step-kicking, and typically worse weather. In general, summer is the best time to make the ascent.
For the Northeast Face, climbers who want ice should go late, but be warned there is a risk of finding "impassable" bergschrunds blocking access to the elegant ice ramp. We made our climb of the face in mid-July, finding reasonable glacier travel, mostly snow climbing, but a few short, fun sections of ice. Climbers on this route in June often don't even rope up for the 700-foot high ramp, as good deep steps can be kicked.
Ouzel Lake makes a great base camp for climbing several peaks in the area, including the elusive Mox Peaks.