My first attempt at climbing Thurston Peak was aborted because of an impassable brushy area. That hike started at Hobo Camp and I do not recommend that approach.
My second attempt, started from Hwy 299 that connects Redding to Eureka on the California coast. This is a beautiful drive along the Trinity River and through Weaverville. Continue west bound on Hwy 299 to the little settlement of Big Bar. There is a ranger station on Hwy 299 in Big Bar and 5.1 miles west of the ranger station is a gravel forest road marked as 5N13.
Turn onto 5N13 and head north. There is a sign at the beginning of the road that says Green Mountain Trailhead 13 miles. That is your destination. Follow this road that any 2WD car can drive. 12.2 miles from Hwy 299 there is a little road to the right with a down sign indicating Green Mountain Trailhead is up that road. The trailhead is up that road but a down tree blocks the road about 100ft from the turn off. Continue straight ahead. At 13.5 miles from Hwy 299 the road ends in a big clearing and a nice camping spot.
On the right side of this clearing is a small road marked 6N19. Head up this road. It is a little rougher and steeper than the road you have been on, but as long as it is dry, you shouldn’t have any problem. Take this road .8 mile to the marked Green Mountain Trailhead on the left. Elevation of the trailhead is 5,130ft.
This route to the Thurston Peaks is easy to follow. The trail is an old overgrown jeep trail, that hasn’t been used by vehicles in at least 50 years. The Green Mountain Trail has easterly and immediately climbs up Brushy Mountain in the first 1.25 miles and gains about 900ft. This is a nice climb under a forest canopy.
After cresting Brushy Mountain, the trail then descends the other side and you lose about 1,000ft in elevation. Remember that on you return, you will have some work to do. The trail then takes a big turn to the north and heads directly at Green Mountain. The trail will ascend the little valley on the east side of Green Mountain. Again, the trail here is nice, but is somewhat overgrown in spots. As you go up this pretty little valley, you will cross a little stream and a couple of springs. This is the only water I saw on this hike.
Follow this trail up to a ridgeline that is east of Green Mountain. This is about 4.25 miles from the start and you gained back the 1,000 feet you lost coming down Brushy Mountain. On this ridgeline, there is a big fork. Left or west takes you up Green Mountain, and right or east takes you to Thurston Peaks. If you’re already tired, turn around and head back to the car.
The trail here is more like an old fire break. It is very wide and follows the ridgeline up and down in a northeasterly direction. At ladder camp, the trail narrows to a regular walking trail as it skirts around the south side of a rocky knob (labeled 1978-T on the topo) for about .5 mile.
At this point you are on a large open saddle and can see a rocky ridge ascending directly east of this saddle. You are done with the trail at this point unless you want to continue to the Hangar’s Roost Campsite. There is no trail to the summit that is about 1,300 feet above you.
Head up the ridge until it gets kind of rocky and then start skirting the rocky areas by dropping off to the south and heading up the talus and scree fields. There are plenty of rocky areas to climb on through this area too, but they are helpful for solid footing to climb up to the ridgeline. Continue up this ridge, picking the best route that fits your style. You have to climb about 1,000 ft before you get to the ridgeline.
At the ridgeline, turn north and head to the summit. This last .25 mile is over a rocky ridgeline and I dropped down a bit to the west to bypass the rocky areas. More talus and scree here, but it was safe.
The summit has great views in all directions. Return to the trailhead by the same route you came up. The total hike is about 16 miles, and the total gain with all the ups and downs is about 5,300 ft. It took me just under 9 hours for this hike. Take lots of water on a hot day….
The 10 essentials and plenty of water.