Ultimate Guide To Sourdough Mountain Trail in Washington, 2022

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Sourdough Mountain Trail is an exhilarating hike up Sourdough Mountain from the trail head at Diablo on the shore of Skagit River, all the way up past the Sourdough Mountain peak and part of the way toward Pierce Mountain peak to the old lookout hut that serves as the mountain’s icon. 

It is rated a difficult trail and mostly because there is a steady increase in elevation from start to finish.  But as it is an in-and-back trail, Sourdough Mountain trail is all downhill on the way back… so, you have that to look forward to!

Over the course of the ten mile hike, you’ll climb nearly a mile into the sky among the mountain peaks as you gain 5100 feet of elevation from trail head to the outlook hut.  As part of the Ross Lake National Recreation Area, Sourdough Mountain trail is well kept and maintained throughout the year. 

Seasonal closures and safety precautions are kept up to date and you will be able to seek access and weather information long before you take the trip up the the lake to start out hiking.  Due to the remote nature, the weather conditions, and the overall rugged nature of Sourdough Mountain trail, it is mostly recommended for hikers during the summer months after the spring thaws melt in early May and before the first snows begin again come late September and early October. 

Once you do reach the top, you’ll have one of the most beautiful views in all of the North Cascade range, with Ross Lake to your east, Diablo Lake to the south, and Mount Prophet, and Elephant Butte to the north.

About The Sourdough Mountain AREA: Fast Facts

  • Location: North Cascades National Park
  • Length: 12.48mi (AllTrails),10.4mi (WTA)
  • Elevation Change: 4271.64ft (AllTrails), 4870ft (WTA)
  • Highest Point: 5985ft (per the Washington Trails Association)
  • Type of Hike: Out & back

HISTORY OF THE Sourdough Mountain AREA

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Whatcom County boasts some of the most pristine mountain hiking trails in the entire Pacific Northwest.  As part of the North Cascades National Park, several prominent peaks speckle the landscape far and wide, and Sourdough Mountain sits in the cradle at the foot of both Ross Lake and Diablo Lake making it and nearby Pierce Mountain subjects to behold from above as well as below. 

The current lookout hut on the ridge between Sourdough Mountain and Pierce Mountains was built in 1933 as a fire lookout. 

The small 203 square foot building is a basic plywood shack, used primarily in the prevention of forest fires but saw new interest at the advent of WWII to also be on the lookout for enemy aircraft coming in from the north.

Once the war was over and other mechanical surveillance techniques were perfected, lookout buildings like this were rendered obsolete and many didn’t last through the 1960s.

The Sourdough Mountain lookout gained some notoriety and fame in the attraction of poets and counter -culture generation embraced the escape into nature and the magical views available from the Sourdough Mountain lookout were captured in the words of Philip Whalen and shared with the poets back home, giving the Sourdough Mountain lookout an aura of being a special place, and one worthy of preservation.  This lookout survives today with occasional repair work keeping it from deteriorating such as a new roof installed in 1980 and the structure has since been entered into the National Register of Historic Places in 1989.

GETTING TO THE Sourdough Mountain TRAIL

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Point your map in the general direction of the little town of Diablo and get yourself on the road toward Sourdough Mountain.  If you’re coming in from the south such as Seattle its about 2 hours and 30 minutes up I-5 to 530 through the winding woods to Rockport and then along 20 all the way up into Diablo.  If you’re coming in from Burlington or other points north such as Bellingham, you’ll come down the I-5 and pick up 20, come right past Rockport into Diablo.

Unfortunately, if you’re coming in from the east, like over from Winthrop and it’s still only late Spring, you’re not going to believe the next thing you read… you will be coming south all the way around Okanogan-Wenatchee and Mount Baker-Snoqualmie as several portions of 20, the North Cascades Highway, are closed off and shut down during the winter.  Yes, this pretty much means the hike to Sourdough Mountain trail is off unless you’re willing to make the six or seven hour drive around to the coast or you wait until the roads are cleared and opened for the season.

Once you make it to Diablo, the Sourdough Mountain trail head is clearly marked and one of the multiple trails in the area that hikers are flocking to.  At the last bend in the Skagit River before you see Diablo open up before you, there is a small parking area on your left as you turn the corner.  From there, the Sourdough Mountain trail head is just to the side of the Ross Lake Resort.

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In and back the entire Sourdough Mountain trail is a total of ten miles, five up, five back.  So the need for regularly dedicated facilities aren’t especially necessary, but the small village-like town surrounding the trail head base is full of friendly stores, public restrooms, and water gathering locations.  There is parking available at the Sourdough Mountain trail head right off Diablo Street behind an old basketball court.

Just over the three mile mark into the hike, you’ll cross Sourdough Creek.  This is a running source of fresh water, but of course, wild water as well.  The Sourdough Campground is nestled into the tree line just off the side of the trail and the creek.  There are no facilities available but if you’ve obtained your backpacking permit, waking up to the views available from this camping location are unbeatable.  No campfires are permitted while hiking anywhere in the area, so if you are backpacking and overnighting, be prepared for the cold evenings without producing a fire.

Don’t expect to find any facilities at the lookout hut either.  This rudimentary building could offer shelter, but that’s about it.  No bathrooms, no electricity, no water.  The tiny building is closed up and not accessible to the public but it serves as the turnaround point for the Sourdough Mountain trail.  Once you reach and enjoy the views from this incredible vantage point, you turnaround and head back down to the Sourdough Mountain trail head where you came in.  It’s a difficult trail to hike, and it is cold and without facilities, but the views from the top are unsurpassed.

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Before undertaking something as notorious as Sourdough Mountain trail, you’re going to do your homework and look up a few facts on line.  We’ll were here to read long and drink deep from that well of knowledge.  You’ll see the profile of the hike and may think to yourself, “oh it’s not that bad, it’s steady and sloping”. 

However, if you don’t consider the scale of that profile you may be dangerously surprised.  You begin to gain elevation at the very first steps onto Sourdough Mountain and you don’t stop climbing until you reach the turnaround point, 5 miles later and just under one mile high.

But don’t get discouraged, though the climb up Sourdough Mountain trail may be difficult, it is rewarding.  The first two miles will bring you up most of the elevation gaining 3000 of the 5000 feet, so if you are looking for a silver lining, not only as the remaining three miles only a gain of 2000 feet.  Yeah, yeah, something about a Pyhrric victory… But seriously, the climb is worth it, stick it out!

That final two miles past the campground and past the Sourdough Creek come above the treeline and with spectacular views down over Diablo Lake and the dam far below.  Once you make it to the iconic Sourdough Mountain lookout, the panoramic vistas will make the entire climb worth every single step. 

Not only is the arduous trek finished, but the return trip is all downhill retracing your steps back to the trailhead.  Take your time at the top, explore the short quarter mile spur off the main trail to the rocky and craggy peak to the northwest just after those last few short switchbacks before the lookout.  While no more spectacular than the rest of the places to look out from, you’ve earned the right to get every bit out of this experience with all those aching, climbing steps up the mountain.

For more incredible hikes in North Cascades, check out our guide to Finding the 10 Best Hikes in North Cascades National Park.

If you’re planning a trip to North Cascades and are looking for a great place to stay, look no further than THE 6 BEST HOTELS NEAR NORTH CASCADES NATIONAL PARK.


Difficult is a matter of perspective.  Is Sourdough Mountain trail difficult to navigate?  No, not really.  There are no major obstacles, there are no immediate dangers as long as you embark on the hike during the summer season and in good weather.  However, the sheer relentless climb with no discernible breaking or resting point is considered by most as a grueling climb and a difficult hike to complete.  Sourdough Mountain trail will challenge you and test your stamina, but once you reach that summit and take in the rarefied air on top, look out over the lakes far below… you’ll know why so many people recommend Sourdough Mountain trail as a worthwhile hike.

Wildlife thrives in the area but they are used to seeing hikers along the trail so they generally won’t roam too far into human interaction.  The iconic lookout hut is considered a worthwhile destination  for the views available from its perch.  Winter hiking is discouraged due to avalanche hazards but snow can persist year round at the peak in the right conditions.  Take care to hike Sourdough Mountain trail safely and securely.  This one is difficult but rewarding, make certain you’re up to the challenge before tackling it.

Next, check out the other top hikes in North Cascades National Park outside the Sourdough Mountain trail by following the links below: