Johannes Peter Letzmann (19 July 1885 – 21 May 1971) was an Estonian meteorologist, and a pioneering tornado researcher.

It generated extensive analysis techniques and insights on tornadoes at a time when there was still very little research on the subject in the United States.

There he built a "Forschungsstelle für atmosphärische Wirbel" (Research Center for Atmospheric Whirls).

In 1962, he elected to retire to a hostel established for former Baltic Germans at Langeoog, an island off the North Sea coast of Germany.

Letzmann's antebellum work remained forgotten for decades until rediscovery beginning in the 1990s.