Humboldt Hill is a census-designated place (CDP) in Humboldt CountyCaliforniaUnited States. Humboldt Hill lies at an elevation of 194 feet (59 m).[2] The population was 3,414 at the 2010 census, up from 3,246 at the 2000 census. The area is in the 95503 zip code and part of unincorporated Eureka.