Oak Mountain consists of a mountain with two peaks, the northern at , taller than the southern at , which is located east of the city of Temecula, dividing Pauba Valley from Butterfield Valley. The two peaks of the mountain are divided by the gorge of Temecula Creek Canyon which has Vail Lake Dam at its head. The Vail Lake reservoir is to the east of its southern peak and southeast of its northern peak and at the base of the mountain. The Black Hills lie to the north of the mountain and Agua Tibia Mountain lies to its south.