Authorities say the baby, wrapped in a plastic bag, was found shortly before noon Tuesday after an apartment resident heard cries and notified the apartment manager, who pulled the child from the dumpster.
The boy was taken to a hospital. Police say he's doing well.
It's unclear how long the child was in the dumpster but temperatures in the area south of Sacramento topped 100 degrees Tuesday.
Police found the baby's 15-year-old mother nearby and she was taken to a hospital. Police say she could face charges of child abuse and endangerment.
Police also note that California law permits newborns to be anonymously left at hospitals or fire stations.