Ultimate 4wd destination: Thunder Mountain in San Bernardino County
Thunder Mountain is a high mountain peak at an elevation of 2.613m (8,572ft) above the sea level, located in San Bernardino County, in the southern portion of the U.S. state of California.
Set high into the San Gabriel Mountains, in Southern California, the dirt road to the summit is totally unpaved. It’s called Thunder Mountain Road. It’s a 2.09km (1.3 miles) long service road to the chairlift. The road ends at the top of the chair lifts. It is a wide road littered with rocks that serves as a ski run during the winter. 4x4 vehicle required.
Tucked away in the Cucamonga Wilderness within Angeles National Forest, near the eastern border of Los Angeles County, the road is usually impassable from late October through late June or early July (depending on snow). The open and close dates all depend on snowmelt and snowfall each year. The drive is very scenic with nice views of Mt. Baldy to the north and the North Fork, Lytle Creek to the east. The road to the summit is very steep, hitting a 22% of maximum gradient through some of the ramps. Starting at Mount Baldy Road, the ascent is 2.09km (1.3 miles) long. Over this distance the elevation gain is 230 meters. The average gradient is 11%.