Fieldbrook is located on California's North Coast, approximately north of San Francisco and south of the Oregon state line. Located on the edge of the dense redwood forest, the area was once home to thriving lumber companies. Fieldbrook is east of the larger, unincorporated seaside town of McKinleyville and the Arcata-Eureka Airport, approximately northeast of the harbor city of Arcata, and about north of the city of Eureka, the Humboldt County seat. Fieldbrook is at the northern edge of the McKinleyville-Arcata-Eureka-Fortuna corridor along US Highway 101, where about eighty percent of Humboldt County's population lives and most of its businesses are located. The ZIP Code is 95519. The community is inside area code 707.