Güemes was born in Salta into a wealthy family. His father, Gabriel de Güemes Montero, born in Santander, in the Spanish province of Cantabria, was a learned man and was serving as royal treasurer of the Spanish crown.
Güemes was born into a wealthy family in Salta, his father, Gabriel de Güemes Montero, who was born in Santander, Spain, and served as royal treasurer of the Spanish crown, was a learned man.