This trail is actually super accessible this time of year. I usually drive right past this trail during summer, because parking is way too crowded. It was super easy to find a parking spot by the trailhead this weekend.

The trailhead is on the other side of the campground. Because the National Park rangers don't maintain the campgrounds during off-season, there were a ton of blowdowns (fallen trees) in the campground to navigate around.

By the parking lot, you'll find information about the route as well as a notice regarding a bridge being out. The creek crossing in question is just on the other side of the campground. If navigating the blowdowns was manageable, you should be able to rock-hop to the other side of the creek without any issue. Alternatively, you can bring waterproof waders to walk through the creek, which has a really low flow rate.

The trail on the other side of the creek crossing is marked with pink ribbon.

The entire trail to Thunder Knob is a series of gentle uphill switchbacks with plenty of trailside benches to stop and enjoy the mountain views.
The trail passes by Thunder Lake which is already frozen over this time of year.

The end of the trail has a couple of viewpoints overlooking Diablo Lake.

There is light patchy snow on the trail but microspikes and snowshoes are not yet required here.

Stats: 4.5 miles RT, 750’ gain, saw no one on the trail and only a few people near the parking area – a very quiet day!

We brought snowshoes and micro spikes, but used neither. The snow was only about 4-6 inches deep in most places making the trail easy to follow. The only place we had trouble staying on trail was near the creek crossing. On the north side of the creek there were orange flags to help us stay on track.

We arrived at the parking area by Colonial Creek campground at 9 am. There is an open, clean, stocked (TP and hand sanitizer) outhouse just behind the Thunder Knob information kiosk. We headed through the closed, northside-of-the-road campground to the Thunder Knob trailhead. We then followed the snowshoe tracks/foot prints toward the creek. At the creek there are a few options for crossing. We veered left and crossed where we could see orange flagging on the north side of the creek. Crossing was pretty easy, but the rocks are very icy and slippery—CROSS WITH CAUTION. Poles definitely helped.

Once across the creek we followed the orange flagging till the trail became very obvious. There are a lot of switchbacks. Peekaboo views through the trees revealed Colonial Peak to the SW, Ruby Mountain to the SE, and to the south the Thunder Creek valley and the Hwy 20 bridge over Diablo Lake.

When we arrived at the first viewpoint, the views of Diablo Lake were limited and the clouds swirled about providing only occasional views of Sourdough Mountain and Davis Peak. Pyramid Peak was completely enshrouded in clouds the entire time. We could look east and see the Diablo Lake overlook on Hwy. 20.  The views south up the Thunder Creek valley were superb.

After a quick snack we headed back, taking an alternate crossing of the creek but it was not any easier so just look for the orange flagging. It was a fun, half day adventure in the snow!

This is a nicely built trail with moderate elevation gain. At the start of the trail, the bridge is out and the trail can be a little hard to find. After crossing, go upstream to find the trail again.

Despite the smokey air, the hike was beautiful. No views because of the smoke, but I’d hike this trail again in a heartbeat. Very well marked, described accurately and the elevation gain was enough to get the blood pumping.

Nice and clear day. Trail was clear and crowds were low. Parking was full but it was easy to park alongside the road. Top of the mountain had a nice breeze and was comfortable. Hiked with a 5 lb. Yorkie so it was easy to handle with lots of other dogs on the trail.