Coombs came to California in 1843, first working for Steven Smith in Bodega Bay; and then for William Gordon at Rancho Quesesosi in Yolo County.
In 1847 Coombs purchased a 325 acres (1.3 km2) farm[1] on Rancho Napa from Salvador Vallejo about one and a half miles north-west of present-day Napa, and where he resided until his death.
Coombs purchased 80 acres (0.3 km2) of Rancho Entre Napa from Nicholas Higuera in 1847.
Coombs and William Gordon purchased Rancho Chimiles from the Berreyesa family in 1851.
His son Frank Coombs was a United States representative from California.