Jacob Weimer, nicknamed "Tornado Jake" (November 29, 1873 – June 19, 1928), was an American professional baseball player.

He played in Major League Baseball as a left-handed pitcher for the Chicago Cubs (1903–1905), Cincinnati Reds (1906–1908) and New York Giants (1909).

[2] In a seven-season career, Weimer posted a 97–69 record with 657 strikeouts and a 2.23 ERA in 1472+2⁄3 innings pitched.

Weimer emerged as one of the Chicago Cubs' top starting pitchers in the first part of the 20th century.

In a trade that benefited both teams, Steinfeld hit .327 to lead the Cubs to their first World Series and Weimer won 20 games for Cincinnati, but eventually faded and was sent to the New York Giants after two subpar seasons.