Sourdough Mountain Lookout

Overview

A classic North Cascades suffer-fest with a huge payoff: Sourdough Mountain Lookout sits high above Diablo Lake with sweeping views that, on a clear day, make the steep grind worth every switchback. The lookout (built in 1933) crowns a ridge of meadows and granite and has inspired writers and fire lookouts alike.

Current Status

As of late 2025, the Sourdough Mountain Trail and access to the lookout remain closed due to damage from the 2023 Sourdough/Stetattle fires. The building itself is closed to the public. Recheck official park alerts before making plans.

The Hike (when open)

• Diablo approach: About 10.2–10.4 miles round trip with roughly 4,870–5,088 feet of gain. Expect unrelenting switchbacks for the first ~3.5 miles, then meadows, Sourdough Creek near Sourdough Camp at 4.2 miles, and a final ridge walk to the lookout with big views over Diablo Lake.
• Pierce Mountain approach: Longer (~9.9 miles from Ross Dam Trailhead) and less steep. The trail follows Ross Lake before climbing through an old 1978 burn and subalpine meadows; near the ridge, the path can be faint—watch for cairns. Tarns near Pierce Mountain Camp are the only water source on this side.
• Loop option: A demanding ~20.5-mile link-up using Sourdough Mountain, Ross Dam, and Diablo Lake trails with brief road connectors near Diablo Dam and the town of Diablo.

Backcountry Camping and Regulations

• Designated camps: Sourdough Camp (4.2 miles from the Diablo side) and Pierce Mountain Camp (~1 mile east of the lookout); both are small (max 4 people) and require backcountry permits. No camping at the lookout; no fires—bring a stove.
• Pets: Allowed on leash only within Ross Lake Recreation Area; not permitted at either camp or the lookout summit.
• Vegetation is fragile—stay on durable surfaces (trail, snow, rock) to protect meadows.

History

A lookout site was established here as early as 1915; the current structure dates to 1933 (Civilian Conservation Corps) and is listed on the National Register of Historic Places. The site was used to test the Osborne Firefinder—equipment that became standard in lookouts— and later inspired poets who staffed the tower in the 1950s.

Conditions, Hazards, and Wildlife

This west-slope landscape is steep, wet, and wild. Early season often means snow lingering near the ridge with weakening snow bridges at Sourdough Creek—routefinding and traction may be needed. Bugs can be fierce in season. Weather can change fast; marine systems bring heavy precipitation, and winter snow is wet and avalanche-prone.

Best Time to Visit

When the area reopens, target mid/late summer into early fall for snow-free meadows and clear views. Start at dawn to beat heat on the lower switchbacks and to have time for the big vertical. Photographers: late-day light over Diablo Lake and the Picket Range can be superb, but plan extra time for the steep descent and bring headlamps.

Practical Notes

Parking for the Diablo approach is in the town of Diablo near the domed swimming pool; the trail starts behind it. There’s typically no restroom at the Diablo trailhead—use facilities earlier along the highway. Water is scarce on the lower Diablo side; refill at Sourdough Creek (treat it) or the tarns by Pierce Mountain Camp on the Ross Lake side.