Mount Thomson - Sept 2025

Aaron and Kyle were up for an ascent of Mount Thomson. We met at 6:30 at Snoqualmie Pass, and it was still quite dark outside – the first time all year that I had to confront the grim reality that peak summer had passed us by.

We took the shortcut up Commonwealth basin, joining up with the PCT and cruising the easy miles below Kendall peak, reaching the Katwalk a bit over 2 hours after leaving the trailhead. It was clear that wildfire smoke was thick to the east, but we had clear skies for the time being.

Approaching Ridge Lake with the top of Thomson visible in the background

We headed out across the Katwalk and were soon passing Ridge Lake and reveling in the flat trail and beautiful day. It wasn’t until we were about a half mile past the turnoff to Bumblebee Pass that any of us realized that we had completely blown past it. Aaron eventually caught on and got us turned around and headed back in the right direction. There’s no telling how far past Bumblebee Pass Kyle and I would have gone without him!

PCT cruising

Back on track now, we climbed up the extremely steep trail to the pass, before descending just as steeply down into the basin below Thomson, which looked intimidating from this vantage point. Here we followed the climber’s path to the shoulder of Thomson at around 5500, climbing up some scree and aiming for a prominent notch in the ridge line. We all noted that the smoke was starting to push west and obscure some of the bigger peaks on the Snoqualmie crest.

Thomson looking intimidating

Aiming for the prominent notch as we near Thomson's east ridge

At this point we got our helmets out and began the scramble portion of our journey. The majority of the climb was on a well-defined climber’s path, rarely exceeding class 2, except for a few short sections. There was a bit of class 3 at about 6200’, which was pretty easily dealt with, but I did notice some slings and rappel rings around a tree at the top of this section. Eventually we came up to the notorious class 4 step, and it did look like it would be a bit tricky. Aaron had climbed Thomson before (thanks for repeating Aaron!) and negotiated the most difficult bit with relative ease. Kyle and I followed, and I found it to be doable and a fun challenge. I was glad to have brought a rope to avoid downclimbing it, though. The final bit to the summit was more class 2, and before we knew it, we were on the summit.

Aaron crushing it on the class 4 section

Kyle near the top of the class 4 bit

Looking down on the hazy Middle Fork

The smoke was really impacting the views, but it was still a really cool position to be in - towering above the Middle Fork and looking toward the hazy and rugged Lemah, Overcoat, Chimney Rock, etc.

Thomson has great views of Overcoat, Chimney Rock, Lemah, etc.

On the descent, Aaron and I chose to rappel the class 4 step. There was fresh webbing and rappel rings, and it eliminated any downclimbing-related stress. Kyle just scampered down and I was very impressed by the ease in which he did it.

Aaron rappelling

The rest of the trip down the ridge was uneventful and we were soon popping up and over Bumblebee Pass and rejoining the PCT. We steamed back to the trailhead, encountering some day-hikers along the way, returning to our cars a little less than 9.5 hours after we left them.

Fall colors on the hike out

It feels great to have checked off this iconic Snoqualmie Pass peak – I might have to come back for the west ridge sometime.

Final Stats: 16.7 miles / 4878 feet of gain

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