(Porto Alegre, 1853 - 1929) was an important Academic painter of Brazil, and the first artist born in Rio Grande do Sul to win international praise for his work.
Born to a family of German immigrants, he began his artistic career as an amateur, helped by his brother Inecio, who was a lithographer, and possibly also by painter Delfim da Câmara. Anyway, in 1878 he moved to Germany in order to study in the Grossherrzoglisch Badische Kunstschule, in Karlsruhe. There he became a pupil of Ferdinand Keller, Theodor Poeckh and Ernst Hildebrand. In 1880 Keller moved to Berlin, being followed by Weingärtner, who then enrolled in the local Academy.
In 1882 he left Germany for France, studying in the Academie Julian under Tony Robert-Fleury and William Adolphe Bouguereau. Wrecked by financial issues, he thought of abandoning his studies, but such situation was reverted by supportive friends, including Baron of Itajube, who got for him a special scholarship from emperor Peter II upon Bouguereau's advice. Then he could further his education in Rome.
Thereafter for many years he divided his time between Rio de Janeiro, Porto Alegre and Rome, traveling very often and being celebrated as one of the most important Brazilian painters of his generation. In Rio Grande do Sul he was a star. In 1920 he was back in Porto Alegre, where the remained until death. His fame declined from 1925 on, facing competition from new painters and changing tastes in local art.