The fall is an excellent time to head to the top of Donner Summit and hike the Mt. Judah Loop Trail. It packs a lot of spectacular views and fun hiking in just six miles, and you will also find a nice smattering of autumn as the brush and small trees are ablaze in color.
The hike begins just at the top of Donner Pass on Old Highway 40. Take the rough paved road to your left and find parking on a small parking area past the Pacific Crest Trail, which will be on your left. The hike dives immediately into lush greenery, or hopefully reddery or yellowery, at this time of year, before beginning a series of short switchbacks up a steep rocky slope.
The trail abates a bit with Lake Mary below to your right, and the slopes of Sugar Bowl straight ahead.The climb is steady, but not too steep and in about a mile you reach the junction with the Judah Loop Trail. Now you begin a four mile loop which will end back at this point. You can go either direction, but for description purposes I will leave the PCT and hang a left. The trail winds and climbs through a forest of hemlock and western white pine to a junction at a saddle in about a mile.
From here, a short side trip brings you to the flat topped Donner Peak, with excellent views of Donner Lake. The main trail starts a switchbacking traverse on a steep slope, eventually coming to the top of the ridge that brings you to Mt. Judah.
From Judah, the views are sublime. To the south is Anderson Peak and Tinker Knob, two highlights of the Pacific Crest Trail between Donner and Squaw Valley. To the southeast is Northstar and to the east is Coldstream Canyon, Truckee and far off in the distance Mt. Rose. Deep below, is the train tunnel where trains travel from Donner Pass to Coldstream Canyon.
With the climbing done, you traverse through view filled splendor past volcanic rock formations interspersed with thick pockets of trees to a junction with the PCT. Turn right and follow the gentle traverse along the slope back to your trail junction and then the last mile back to your car.