Mount Cumulus is situated in the heart of the Never Summer Range on the long spine of mountains that forms the boundary between Never Summer Wilderness to the west and Rocky Mountain National Park to the east. This spine of mountains also forms the continental divide - however the watershed to the west of the ridge drains into the Atlantic Ocean and the watershed to the east of the ridge drains into the Pacific Ocean. Don’t believe me? Check it out.
Mount Cumulus can be a bit of a grunt to get to because the most straightforward approach from the Opposition Creek Basin involves a pretty serious bushwack followed by a long and arduous slog up a seemingly never-ending boulder and talus slope. However, once on the summit you are treated to great views and great ridges that head in both directions. Take the North Ridge (Howard Mountain's South Ridge) to Howard Mountain (where you'll find a much more pleasant descent option) or the South Ridge to Mount Nimbus and beyond. If you've spent the time and energy to get to the top of Cumulus you'll certainly want to bag as many of the neighboring peaks as possible.
Most climbers will approach from the east at the Colorado River Trailhead in Rocky Mountain National Park. This trailhead is well signed and is about an hour’s drive from either east side entrance or about 15-minute drive from the Grand Lake entrance.
From the trailhead follow the Colorado River Trail for one half of a mile to the Red Mountain Trail junction. Follow the Red Mountain Trail for another 2.8 miles until you reach the Grand Ditch (a large canal that diverts water from the west to the east side of the Continental Divide).
At the canal take a left so you're headed generally south. After about a mile of hiking down the maintenance road look for a bridge across the ditch that leads to the Opposition Creek Backcountry Camp Site. Follow a trail past the campsite and continue upward along Opposition Creek. The faint trail peters out after a while and you're on your own. Continue upward, staying on the north side of any major streams you encounter. After a while you should attain a boulder-strewn valley that steepens into a boulder-strewn gully. You can either scramble up the boulders or bushwack your way through the forest to climber's right of the boulders. This will take you away from Opposition Creek which continues toward the southwest.
After ascending this steep slope/gully you should attain a high meadow. From there Mount Cumulus should be in view. Choose the path of least resistence across talus and boulders.
See the Mount Nimbus Page for more photos of the terrain in the Opposition Creek Basin.
No permits are required to hike/climb Mount Nimbus, but if you pass through the park entrance gates during business hours you will have to buy a park pass. These are $20 for a week long pass, or $35 for an annual pass.
Camping in the RMNP backcountry is allowed in designated campsites only and requires a permit.
Fees for admission ot RMNP
Basic RMNP Rules/Regulations
When To Climb / Mountain Conditions
The Never Summer Range holds snow well into early summer so to avoid snow Mount Cumulus is best climbed July through September. That said, the presence of snow might make the approach and ascent of Mount Cumulus from the Opposition Creek basin easier. Climbing the upper slopes of Mount Cumulus on snow would probably be preferable to the talus you'll encounter during the summer months. However, deep snow below timber line might make that part of the approach a real grunt. Pick your poison.
For current conditions contact Rocky Mountain National Park at 970-586-1206.
Camping in Rocky Mountain National Park is allowed in designated campsites only and requires a permit. To obtain a permit contact the backcountry office at 970-586-1242.