Page Type Page Type: Mountain/Rock
Location Lat/Lon: 48.99800°N / 119.939°W
Additional Information Elevation: 8138 ft / 2480 m
Sign the Climber's Log


Armstrong Mountain lies in the eastern reaches of the northern Cascade Range, astride the U.S.-Canada border, near the northeastern corner of the vast Pasayten Wilderness area in north central Washington. It is the highest summit in its vicinity, with the nearest higher mountains, Windy Peak to the south, and Snowy Mountain, across the border in British Columbia to the north, each about 5 miles away. As such, views from the plateau-like summit are expansive, to put it mildly. In addition to the eastern Pasayten Wilderness and adjacent areas of British Columbia, clear weather views extend far in all directions, including Glacier Peak, 85 miles to the southwest. Though requiring an approach hike of about 7 miles, Armstrong is certainly one most easily attained summits of its elevation in Washington. It is an enjoyable cross country hike up through tundra-like meadows from Horseshoe Basin, a vast meadowland just to the south, which provides basecamps for more extended explorations of the area. Backpackers visiting the Horseshoe Basin area often make the trip to the top, but there is never a crowd. While the south, east and west slopes are hiker territory, the north side, just over the border in Canada, features rocky bluffs above boulders and scree, with a small lake at the base. Of geologic interest are areas of felsenmeer on much of the summit area, attesting to the arctic-like climate. Of geographic interest are the presence of boundary monuments, and the “border strip,” the narrow corridor of cut forest, which is visible for miles to the east and west, marking U.S.- Canada boundary.

Getting There

Unless one lives along the east slope of the northern Cascades, it is a long haul to reach this area. U.S. highway 97 is the major north-south route along the east margin of the Cascades. In its northernmost segment, north from Wenatchee, Washington, it follows the canyon of the Columbia River, and then the valley of the Okanagan River north to the Canadian border. About 20 miles south of the border, at the town of Tonasket, at which is an Okanagan National Forest District office, cross the Okanagan River to the west side and proceed north, meeting the Loomis-Oroville road, and turning westward to the village of Loomis, passing several slender lakes along the way. Just to the northeast of Loomis, locate the Toats Coulee Road, currently numbered Okanagan National Forest Road #39, and follow it up into the mountains, first on asphalt, then gravel, to the junction with the Iron Gate road, currently #3900-500. Turn right onto this rough road, which leads about 7 miles to the Iron Gate trailhead, at about 6,100 feet elevation. A high-clearance vehicle is recommended for the Iron Gate road. From the Iron Gate trailhead, about 7 miles of easy hiking on the Boundary Trail, #533, leads through 7,200 foot Sunny Pass, and on to Horseshoe Basin, a broad, tree-dotted meadowland with elevations ranging from about 6,500 to 7,000 feet. Armstrong Mountain is the broad, meadowy, flat-topped mountain to the north. From the the closest approach of the Boundary Trail along its southern slope, the summit is reached by a simple off-trail hike of about a mile and a half.

Red Tape

A Northwest Forest Pass (aka Trail Park Pass) is required for trailhead parking. This can be obtained at any Forest Service office, and at many outdoor equipment retailers, such as REI. No permits are required for entry into the Pasayten Wilderness.

When To Climb

Periods of settled weather during the summer and early autumn are the optimal times for visiting this area. The remote location, lengthy approaches, and arctic-like weather restrict access during the cold season to all but the more determined winter backcountry travelers. Ski touring is done by some during the spring season, when the weather is less severe. Summer afternoons can be hot and buggy, but the high elevation generally makes for cool to chilly nights, and vast, beautiful fields of wildflowers provide compensation. Autumn brings cooler conditions, with frosty nights, and colorful displays of crimson huckleberry and golden alpine larch painting the landscape. As in all areas of the North Cascades, conditions can change rapidly, and snow may occur at any time of the year. Since most trips to this locale usually involve two days or more, it is advisable to be prepared for a variety of weather conditions.


The Horseshoe Basin area provides almost unlimited campsites to the climber and backpacker. Melting snowbanks usually provide water through mid-summer. Several year-round water sources are present, including a few small creeks, and Smith Lake, located about a mile to the east. A shallower pond, Louden Lake, located near the south base of Armstrong Mountain, provides an early season water source, but often dries up by late summer.

Mountain Conditions

The remoteness of this area precludes an accurate local forecast for the mountain itself, but general weather conditions for the region can be found at the National Weather Service website forecast for the Eastern Slopes of the Northern Cascades (click here). As noted in “When to Climb,” while conditions can be highly variable, summer and early autumn usually offer the best.