Black Mountain, also known as Mount Day, is a mountain in the Diablo Range

Diablo Range

The Diablo Range is a mountain range in the California Coast Ranges subdivision of the Pacific Coast Ranges. It is located in the eastern San Francisco Bay area south to the Salinas Valley area of northern California, the United States.-Geography:...

 of eastern Santa Clara County

Santa Clara County, California

Santa Clara County is a county located at the southern end of the San Francisco Bay Area in the U.S. state of California. As of 2010 it had a population of 1,781,642. The county seat is San Jose. The highly urbanized Santa Clara Valley within Santa Clara County is also known as Silicon Valley...

, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, east of Poverty Ridge

Poverty Ridge

Poverty Ridge is a ridge in unincorporated Santa Clara County, California, east of Milpitas. Calaveras Valley lies to its west, while its east side slopes down to meet Arroyo Hondo. Creeks that originate on Poverty Ridge include Calaveras and Penitencia Creeks....

 and Arroyo Hondo

Arroyo Hondo (Santa Clara County, California)

Arroyo Hondo is a river in Santa Clara County, California, United States, that lies east of Milpitas. The area is privately owned by the San Francisco Water Department and is closed to public access because of its usage as drinking water. Bounded to the east by Oak Ridge and to the west by Poverty...

, and about 10 miles (16.1 km) from Milpitas

Milpitas, California

Milpitas is a city in Santa Clara County, California. It is a suburb of the major city of San Jose, California. It is located with San Jose to its south and Fremont to its north, at the eastern end of State Route 237 and generally between Interstates 680 and 880 which run roughly north/south...

.

The peak is one of the highest in area. The northern half of Black Mountain is an oak woodlands while the southern half is barren. Black Mountain can be clearly seen from most parts of the Santa Clara Valley

Santa Clara Valley

The Santa Clara Valley is a valley just south of the San Francisco Bay in Northern California in the United States. Much of Santa Clara County and its county seat, San José, are in the Santa Clara Valley. The valley was originally known as the Valley of Heart’s Delight for its high concentration...

 including Sunnyvale

Sunnyvale, California

Sunnyvale is a city in Santa Clara County, California, United States. It is one of the major cities that make up the Silicon Valley located in the San Francisco Bay Area...

, Cupertino

Cupertino, California

Cupertino is an affluent suburban city in Santa Clara County, California in the U.S., directly west of San Jose on the western edge of the Santa Clara Valley with portions extending into the foothills of the Santa Cruz Mountains. The population was 58,302 at the time of the 2010 census. Forbes...

, Mountain View

Mountain View, California

-Downtown:Mountain View has a pedestrian-friendly downtown centered on Castro Street. The downtown area consists of the seven blocks of Castro Street from the Downtown Mountain View Station transit center in the north to the intersection with El Camino Real in the south...

 and San Jose

San Jose, California

San Jose is the third-largest city in California, the tenth-largest in the U.S., and the county seat of Santa Clara County which is located at the southern end of San Francisco Bay...

. The peak is visible from the Mount Hamilton

Mount Hamilton (California)

Mount Hamilton is a mountain in California's Diablo Range, in Santa Clara County, California. Mount Hamilton, at is the tallest mountain overlooking Silicon Valley, and is the site of Lick Observatory, the first permanently occupied mountain-top observatory. The various summits along its...

 and Monument Peak.