Tomyhoi Peak, Southeast Route (3rd, ~13.5 miles, 5600 ft gain/loss)

Tomyhoi Peak

Route:

Southeast Route

3rd, ~13.5 miles, 5600 ft gain/loss

I've climbed to this summit three or four times over the years: at 7 years old with my dad (probably stopped short of summit), at 18 years old with my dad, at 23 years old with my cousin, and at 42 years old as a detour while hiking with my mom.

Region: Washington
Elev: 7,435 ft
Rock type: Greenstone
Type: 
Trip Report 1:
Date(s): September 24, 2006 (Sun)
Partner(s): Lisa Doubet
Trip Report 2:
Date(s): August 10, 2025 (Sun)
Partner(s): solo, Sue Abegg (to Tomyhoi arm)

Route Overlay

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Map & GPS Track

GPS Track from my 2025 ascent.

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Trip Reports for Tomyhoi Peak

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In 1990, when I was seven, my parents took my sister and me on a backpacking trip along the Keep Kool Trail near Yellow Aster Butte and Tomyhoi. There’s a photo of my dad with my sister and me titled “climbing Tomyhoi Peak,” though I doubt we actually went to the summit. Below are a few shots from that beautiful family adventure.

Photos

While going through the old photo archives for the 1990 Tomyhoi trip, I stumbled across some shots from 2001. Turns out I actually summited Tomyhoi that year with my dad, during an overnight trip to the area with my parents. Photos below.

Photos

Intro

My favorite part about early autumn where I live is hiking in the North Cascades. So when September 24 looked like it would be a sunny and warm day, it was no surprise that I found myself planning a hike/climb with my cousin Lisa. The plan was to hike 3 miles into the Yellow Aster Butte area and continue up to Tomyhoi Peak, a Class 3 scramble about 3 miles from Yellow Aster Butte, near the American-Canadian Border. My Mother Sue, Aunt Barb, Uncle Scott, and Cousin’s Friend Kristen came along with Lisa and me to spend the day on the lower arm of Tomyhoi while Lisa and I climbed. We planned on a 9 hour round trip from the road for the climb, which turned out to be pretty accurate. Here is a brief timeline of our climb:
  • 8:45 am - leave trailhead (3,600 ft) of Yellow Aster Butte Trail.
  • 10:45 am - arrive at arm just below Yellow Aster Butte, around 5,200 ft.
  • 11:45 am - Aunt Barb, Uncle Scott, Mommy Sue, and Friend Kristen find a nice place on the lower Tomyhoi Arm to stay while Lisa and I climb.
  • 1:35 pm - Lisa and I arrive on summit (7,435 ft) (just under 5 hours from road at a relaxed pace).
  • 2:01 pm - Lisa and I head down from summit.
  • 6:05 pm - arrive back at car.
  • 7:15 pm - my mom and I arrive at the Sumas border crossing to find a lineup extending out the south end of the town, due to a murder suspect that was thought to be escaping into Canada. This was the longest border wait I have ever experienced. But at least we were able to get home eventually (apparently the timorous Blaine border crossing guards refused to work, saying that without guns they "felt unsafe" (a likely excuse--I think they all saw the nice weather and decided they wanted to go hiking. Perhaps this was why there were so many people climbing Tomyhoi—all those Blaine border guards…)).
Below are some photos from the hike/climb. The autumn colors were beautiful.

Photos

Intro

I was visiting my parents between climbing objectives, and my mom and I decided to go for a hike. We settled on Tomyhoi Peak — she had never summited it. My plan was to hike to the top, tag the summit, and then descend to meet her. If she was still feeling good and close enough, I’d head back up with her.

It turned out to be a big day — about 5,600 feet of elevation gain/loss over roughly 13.5 miles, according to my Garmin. My mom made it high on Tomyhoi Arm before turning around, which was still impressive: around 4,500 feet of elevation gain/loss and 12 miles. We paused there for lunch, soaking in the views on what was an unusually hot day for the mountains. On the way out, we enjoyed the glorious sight of Mount Baker and Mount Shuksan across the valley.

Along the way I passed a few parties heading up. At the summit, I found myself in the middle of a once-a-year “nuptial flight” of Formica aserva — an alpine ant mating ritual known as “hill topping,” where swarms gather on high points to find mates. I had stumbled into an alpine ant singles mixer — though one with short-lived romance, as the males die shortly after mating.

Below are photos from a beautiful day in the North Cascades with my mom.

Time Stats

Times
Leave trailhead: 8:08 am
Summit Tomyhoi: 11:22-11:29 am
Back to car: 3:43 pm
Splits
Trailhead to summit: 3 hours 14 minutes
Total time (includes long lunch break with mom): 7 hours 35 minutes

Photos

Videos

Comments Pertaining to this Page / Trip Report

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