The Lompoc field follows the line of the Purisima Hills, a northwest-to-southeast trending range dividing the Santa Ynez Valley on the south from the Los Alamos Valley to the north, and the field is about five miles (8 km) long by one-half to one mile (1.6 km) across.
A small discontiguous part of the field, the Northwest Area, is situated about a mile and a half northwest of the main part of the field, close to the main gate of Vandenberg Air Force Base.